The large-scale application of silica aerogels is restricted due to many reasons, one of which is the poor mechanical. How to exert superiority of aerogels in application has always been the focus of research. In this work, the silica aerogel microspheres were added into polyimide to prepare composite film successfully. The results showed that the thermal conductivity of composite film was declined compared with that of pure polyimide film and kept decreasing with increasing additions, the lowest value was 0.321 W m_-1 K_-1. The mechanical strength is weakened compared with that of pure polyimide film. Therefore, the trade-off between thermal insulation performance and mechanical property is important in application of such film materials. The study enriches the application form of aerogels.