Due to the low thermal conductivity of traditional resin-based composite materials, the thermal resistance of composite casing is large, the heat dissipation is slow, and there are bottleneck problems such as difficult heat transfer, too high local temperature, material softening and structural failure, which seriously restrict the further application of composites in helicopter transmission casing. In view of this, this paper carried out the optimization research on the thermal performance of metal-reinforced resin-based thermoplastic composite casing, which shows that compared with the traditional aluminum alloy casing, the metal-filled composite casing maintains good heat dissipation and reduces the weight by about 15%; compared with the pure resin casing, the maximum temperature performance is reduced by 69.4%, effectively improving the heat dissipation performance.