First of all, China -did- adopt western technology and at least made an attempt to adopt western governance. This is what the Chinese northern army looked like by the late 1800s/early 1900s:
As you can see they looked very much like contemporary European forces with western weapons. The reason being that the Chinese did make a concerted effort to produce a western level army, and succeeded to the extent that it was the modernized Beiyang army which ended the Qing dynasty in 1911.
This is what a ship of the Chinese Beiyang navy looked like:
This -should- look modern because the Chinese actually bought it (along with quite a few other ships) from the Germans in order to build a modern naval force.
So the Chinese did westernized and modernize at least a portion of their state and armed forces, the problem is that they didn't do it as -successfully- as the Japanese. And I go into an explanation of why here:
https://www.reddit.com/r/AskHistorians/comments/53pbe1/why_was_feudal_japan_able_to_quickly/
A better question would be why didn't the Meiji Restoration, or something similar, happen in China?
To that extent, the Qing government did try (Hundred Day Reform), but ultimately failed because 1) conservatism was still too strong, 2) the Empress Dowager Cixi felt threatened by the radicalism of the reformers, 3.) the reformers were overzealous.
This question has been discussed before: