A novel high-temperature resistant carbon fiber/bismaleimide resin composite shell is proposed and its bistable characteristics are studied in megathermal environment. Bistable structures are prepared with epoxy resin composites conventionally, which prone to undergone glass transition at high temperature. The study of high-temperature resistant bistable structure become necessary to suit aerospace field. In this work, the effect of elevated temperatures and different ply angles were investigated on curvatures and snap behaviors of carbon fiber/bismaleimide resin composite bistable shells through experiment and finite element analysis. These results provided significant understanding of morphing behaviors for the carbon fiber/bismaleimide bistable structure in megathermal environment.