OP, is it legal to build Bitcoin mining farm, especially inside China? I heard that China government just tracked and shut down several Bitcoin mining farms recently.
Anyway, I wish you all the best with this project.
PS: Love your long term vision and hope everything turns out well

The Chinese government defines Bitcoin as "digital commodity". It's legal to hold, buy, sell or produce such "digital commodity".
The reason that the government call stop ICOs and shutdown the exchanges is there are two many cheating, manipulating the market, etc.
So it's total legal to build and operating mining farms in China.