Abstract: Solar Dynamic Power System is to be the space energy system in the future.The heat receiver is one of the SDPS key parts.Phase change thermal storage is used in heat receiver.The energy analysis can be used to understand the energy transfer in heat receiver and the thermal storage in PCM.The heat receiver cavity radiation mathematical model and the gas tube heat model were established.Heat loss,energy absorbed by gas,the latent and sensible thermal storage in PCM,tube maximum temperature,gas exit temperature and liquid PCM fraction were calculated.The results were analysed and could be used in heat receiver designing.