So as I understand it, Chinese emperors had two groups of advisers, the eunuchs and the scholar-officials (in period dramas they often sit in groups on opposite sides of the emperor's court). The scholar officials are top-scorers in the difficult and rigorous imperial examination system, and have studied for them since a very early age. But what sort of training did the eunuchs have?
This really depended on the time period and the eunuch's background as well. I must first preface though, that the intention of eunuchs during the late Empire was never originally to serve as advisors to the emperor or his court. Eunuchs were first and foremost, intended to be used as servants. Upper-class Chinese men often had more than one woman in their household, and the Imperial harem often had so many women that a ranking structure was necessitated. To prevent the birthing of children not of the emperor's own making, no men were allowed to reside within the Forbidden City unless they were the emperor himself (and eunuchs). Eunuchs, without their cocks or balls, obviously could not father children, and so they were employed en masse throughout the palace to do a variety of menial tasks, from serving food, to watching over children, to attending to the emperor's harem and importantly, often to entertain the emperor himself. Because eunuchs were often in close proximity to the imperial family, and because eunuchs often served as companions to the emperor in non-formal settings, it wasn't uncommon for emperors to befriend them. I don't know about you, but when my friends give me suggestions or talk to me, I listen. It's not that surprising then, to see why eunuchs could have such an influential presence within the imperial court.
Boys and occasionally men who were castrated, both voluntarily and by force, and then sent to the Chinese court were often of low class, and thus very often, did not have much in the way of education. Wei Zhongxian, the notorious court eunuch who dominated the 6 1/2 years of the Tianqi emperor's reign, was illiterate for instance. The Hongwu emperor or Ming Taizu was deeply distrustful of court eunuchs and ordered that they be kept illiterate to prevent them from meddling too much in state affairs (clearly, not only did illiteracy not stop them, but subsequent emperors and Taizu himself often failed to uphold these guidelines). Once in the court, they were most often just trained to fill their roles as mostly menial laborers, completing a variety of tasks within the palace. One of the reasons why castration was a trend amongst lower-class Chinese was because becoming a eunuch was seen as a way to move up the social ladder for the ethnic Han. Eunuchs who rendered diligent service to the emperor could often bring about great reward for their families (including elevation into the peerage), and initial human offerings were always rewarded monetarily or otherwise.
But not all Ming eunuchs were illiterate and uncultured heathens. Like I said, the guideline of maintaining total illiteracy within the eunuch class was not often adhered to. During Taizu's own lifetime, eunuchs in service to Ming princes could be and were often educated in princely courts, and Admiral Zheng He was one such case, having been tutored under the patronage of the Prince of Yan, later the Yongle Emperor. The Yongle Emperor in particular was notorious for favoring eunuchs in his court, and he trained and employed many of them as spies, most famously within the Eastern Depot, and later on the Chenghua emperor's Western Depot. Eunuchs were also organized into their own yamen, with eunuch staffers working within the bureaucratic office, thus implying that there were eunuchs who had received at least some degree of formal Chinese education.
The Qing dynasty was far more strict in their employment of eunuchs, and they laid down many more, far more rigorous guidelines for eunuchs in service to the Qing court. Can't really say much about them though, I don't know much about the Qing dynasty.
Sorry this answer is a bit scrambled, but in short, the training eunuchs received varied widely. Some received an education that could be deemed on-par with a classic Confucian education, while others received basically enough for them to wipe the emperor's ass.
Sources (abridged Reddit style):
The Cambridge History of China: Volume 9. Edited by Peterson, W. J. Cambridge University Press. 2008
Inside the World of the Eunuch: A Social History of the Emperor's Servants in Qing China. Dale, M. S., Hong Kong University Press. 2018
This really depended on the time period and the eunuch's background as well. I must first preface though, that the intention of eunuchs during the late Empire was never originally to serve as advisors to the emperor or his court. Eunuchs were first and foremost, intended to be used as servants. Upper-class Chinese men often had more than one woman in their household, and the Imperial harem often had so many women that a ranking structure was necessitated. To prevent the birthing of children not of the emperor's own making, no men were allowed to reside within the Forbidden City unless they were the emperor himself. Eunuchs, without their cocks or balls, obviously could not father children, and so they were employed en masse throughout the palace to do a variety of menial tasks, from serving food, to watching over children, to attending to the emperor's harem and importantly, often to entertain the emperor himself. Because eunuchs were often in close proximity to the imperial family, and because eunuchs often served as companions to the emperor in non-formal settings, it wasn't uncommon for emperors to befriend them. I don't know about you, but when my friends give me suggestions or talk to me, I listen. It's not that surprising then, to see why eunuchs could have such an influential presence within the imperial court.
Boys and occasionally men who were castrated, both voluntarily and by force, and then sent to the Chinese court were often of low class, and thus very often, they often did not have much in the way of education. Wei Zhongxian, the notorious court eunuch who dominated the 6 1/2 years of the Tianqi emperor's reign, was illiterate for instance. The Hongwu emperor or Ming Taizu was deeply distrustful of court eunuchs and ordered that they be kept illiterate to prevent them from meddling too much in state affairs (clearly, not only did illiteracy stop them, but subsequent emperors and Taizu himself often failed to uphold these guidelines). Once in the court, they were most often just trained to fill their roles as mostly menial laborers, completing a variety of tasks within the palace. One of the reasons why castration was a trend amongst lower-class Chinese was because becoming a eunuch was seen as a way to move up the social ladder for the ethnic Han. Eunuchs who rendered diligent service to the emperor could often bring about great reward for their families (including elevation into the peerage), and initial human offerings were always rewarded monetarily or otherwise.
But not all Ming eunuchs were illiterate and uncultured heathens. Like I said, the guideline of maintaining total illiteracy within the eunuch class was not often adhered to. During Taizu's own lifetime, eunuchs in service to Ming princes could be and were often educated in princely courts, and Admiral Zheng He was one such case, having been tutored under the patronage of the Prince of Yan, later the Yongle Emperor. The Yongle Emperor in particular was notorious for favoring eunuchs in his court, and he trained and employed many of them as spies, most famously within the Eastern Depot, and later on the Chenghua emperor's Western Depot. Eunuchs were also organized into their own yamen, with eunuch staffers working within the bureaucratic office, thus implying that there were eunuchs who had received at least some degree of formal Chinese education.
The Qing dynasty was far more strict in their employment of eunuchs, and they laid down many more, far more rigorous guidelines for eunuchs in service to the Qing court. Can't really say much about them though, I don't know much about the Qing dynasty.
Sorry this answer is a bit scrambled, but in short, the training eunuchs received varied widely. Some received an education that could be deemed on-par with a classic Confucian education, while others received basically enough for them to wipe the emperor's ass.
Sources (abridged Reddit style):
The Cambridge History of China: Volume 9. Edited by Peterson, W. J. Cambridge University Press. 2008
Inside the World of the Eunuch: A Social History of the Emperor's Servants in Qing China. Dale, M. S., Hong Kong University Press. 2018