This paper presents an idea about combined phase change material room, which lays two different kinds of phase change material(PCM) in building envelopes of different orientation. The two PCMs occur phase transition separately in winter and summer. The experimental rooms of combined phase change material and ordinary material are built and the experiment is done for summer condition. Measurement and calculation are done to indoor air temperature and convection and radiation heat fluxes of the combined PCM room. Comparison is done with ordinary room. Results show that this new type of room can effectively improve indoor thermal environment during summer, thermal performance of the building envelopes also shows some differences with ordinary room.