is courses and assignments in Peking university of Qing hua university all conducted in Chinese?

Of course not. They teach some courses in English. For more details, I suggest you find at the official webistes of both.

I have tried looking for it at the official website but it wasn't mentioned. Any idea how else I can look for it? Usually how much are the rent for a small place there per month?

Oh, really, but I think I find the related information on the website of Peking University.
In Peking University, Master Program in Public Policy, Master Program in Public Policy, Guanghua International PHD Programme, MBA, Master Program in Public Policy, International Relations MIR Program Prospectus and PKU-Sciences Po Double Degree are taught in English. Expect these courses, other majors and course all use Chinense.
If you want to rent apartment on your own, the cost is around 1500 to 2000RMB per month. It is suggested to live in the dorm in the campus, which is cheap and convenient. The environment is nice, too.

Thanks Shasha. Your comment is very helpful. any idea which uni in china is good for agricultural courses?

Oh, then I recommend China Agriculture and Northwest University of Agriculture and Forest to you.