Is there any Muslim restaurants in Changchun?

Yes, there are several Muslim restaurants nearby the university. Don't worry.
Hui Hui Xiang Restaurant and Alibaba Xiao Chu are popular ones. You can find authentic halal foods there. And the dishes have reasonable prices.
Hui Hui Xiang Restaurant: the intersection of Longli Road and Yueyang Street
Alibaba Xiao Chu: No.5, Shilin Food City, 20 meters eastward of the intersection of Tongzhi Street and Guilin Road.
Hope you like. :)