Bismaleimide resin composites service as primary high temperature resistance load-carrying structure in aerospace crafts. Dynamic cure kinetics of highly reactived 802 bismaleimide resin was analyzed by differential scanning calorimetry, meanwhile its cure cycle was established as “150℃/1 h+180℃/2 h+200℃/4 h”. The T _g of 802 resin is up to 325℃ cured at 200℃, significantly superior to XU292 resin (234℃) with the same curing temperature. Furthermore, MT300/802 composite mechanical properties were investigated at room temperature, 230, 280 and 300℃, respectively. Its flexural strength retention capacity is 57% at 280℃, and the 300℃ flexural strength is as high as 1 094 MPa. Meanwhile, its interlaminar and in-plane shear strength also exhibits high properties level at both room temperature and high temperature. The results indicate that MT300/802 composite has the feature of “low temperature curing and high temperature usage”, which is suitable for aerospace primary structures.