A kind of MT300/902 polyimide composite was prepared by autoclave molding process, and the effect of three different process parameters (pressing temperature, pressure, curing temperature) on mechanical properties were examined. The influence of process parameters on properties of polyimide composite was studied. According to the results, the best pressing temperature of MT300/902 polyimide composite was 240~260℃, pressure range was not lower than 1.2MPa, and the best curing temperature was 310~330℃. Using the best process parameters, MT300/902 polyimide composite with better mechanical properties and high quality (defect area is less than 2%) than the original and polyimide composite structures were prepared.