The windmill appears in China during the Song Dynasty, in the early 12th century. These were vertical-axis windmills probably inspired by the Central Asian (AKA Persian) vertical axis windmill. Needham (1974) notes Chinese knowledge of the Central Asian windmill in the early 13th century, but as Zhang (2009) notes (and see also Sun (2009)), it was already in use in southern China by that time.

The Chinese windmill might be an independently-developed design, inspired by descriptions of the Central Asian windmill, rather than a direct copy. There are major differences. Notably, the Central Asia windmill is built in a tower, with the tower partly shielding the sails to provide the asymmetry needed for rotation. The Chinese windmill uses movable sails to produce the same asymmetry, and doesn't need to be partly enclosed in a tower. (The tower is useful for controlling the speed - the openings can be closed to stop the windmill, or partly closed to reduce the speed, which can be important in high winds.)

Central Asian windmill: https://www.youtube.com/watch?v=lhjww8FBsZk

Chinese windmill: https://amc.stust.edu.tw/en/node/t01 (modern reconstruction at Southern Taiwan University of Science and Technology)

The main use of the Central Asia windmill was grinding grain; the Chinese windmill was mostly used for pumping water (mostly for irrigation, but also for salt-making). These vertical axis windmills were used in China into the 1960s, when they were replaced by modern electric pumps.

From the late Ming, horizontal-axis windmills were in use on the southern coast. Needham writes that these were probably adapted from Dutch designs. Notably, these aren't true horizontal-axis windmills, but oblique-axis windmills. In the Dutch version (which was in use when the Chinese versions first appear), the oblique axle was directly connected to an Archimedean screw pump (so not needing any intervening gears). The Chinese version retains the oblique axis, but uses a system of gears to drive a traditional Chinese pump (Sun, 2009).

References (all with pictures of windmills):

Needham J (1974) Science and civilization in China (Volume IV: 2), Cambridge University Press, London, UK.

Sun L., Zhang B., Lin TY., Zhang Z. (2009) An Investigation and Reconstruction of Traditional Vertical-Axle-Styled “Chinese Great Windmill” and Its Square-Pallet Chain-Pump. In: Yan HS., Ceccarelli M. (eds) International Symposium on History of Machines and Mechanisms. Springer, Dordrecht

Zhang B. (2009) Ancient Chinese Windmills. In: Yan HS., Ceccarelli M. (eds) International Symposium on History of Machines and Mechanisms. Springer, Dordrecht