Abstract: In order to study the application of composite phase change materials with nano particles and the temperature control performance of spaceborne active equipment in phase change control, uses the numerical simulation method to compare the temperature control performance of stearyl alcohol modified Graphene/n-octadecane paraffin composite phase change materials with that of pure n-octadecane paraffin phase change materials. The results show that the composite phase change material has certain advantages when temperature is controlled for a short time. At the same time, when the active components dissipate heat during non working hours, the composite phase change material can dissipate all the heat absorbed during working hours in a shorter time, and the speed of restoring the initial state is 14.1% faster than that of pure Octadecane paraffin. Therefore, the composite phase change material with stearyl alcohol modified Graphene nanoparticles can be an effective auxiliary means to improve the overall performance of the phase change temperature control device; at the same time, a comparative analysis was conducted on the temperature control performance after combining with other main methods to improve thermal conductivity. Composite phase change materials can play a role in improving the performance of temperature control devices and can be effectively combined with other methods.