Is it hard to get Halal foods in Shanghai? Can you recommend any best chinese muslim foods?

No, as I know, there are many nice halal food restaurants. You can find some easily.
Among them, Yelixiali Xinjiang Restaurant and Gulixian Halal Restaurant win high popularity among local people. They provide authentic halal foods. And the prices are reasonable.
Both of them have several branches in this city. For example:
Yelixiali Xinjiang Restaurant:
A.2nd Floor, Hongxin Fashion Plaza, No.762, Tianshan Road.
B.No.17 to 18, 2nd Floor, Super Brand Mall, West Lujiazui Road.

Gulixian Halal Restaurant:
A. 3rd Floor, Pudong Food City, No.601, Zhangyang Road
B. Room 508, Building No.12, Daning International Plaza, No.2008, Gonghexin Road.
Hope you like. :-)

Hi Carol! thank you for your prompt reply. your info is really helpful, appreciate it so much :)