In this study, stearic acid (CA-SA) was used as phase change material (PCM), carbon nanotubes and nitriding (CNT, BN) as support materials to prepare CNT-BN-SA-1 composites by vacuum impregnation. According to the results of the thermal conductivity of CNT-BN-SA-1, the maximum thermal conductivity of CNT-BN-SA-1 is 0.83 Wm/k when the CNT-BN content reaches 15 wt%. The surface morphology, heat storage capacity and reliability of CNT-BN-SA-1 were systematically studied. The melting temperature (ΔTm) of CNT-BN-SA-1 is 51.83°C and the latent calorific value is 143.5 J/g. CNT-BN-SA-1 still exhibits good latent heat capacity after 1000 heat treatment cycles, and its latent heat after cycling is 147.3 J/g. After a high temperature of 100°C, CNT-BN-SA-1 still retains a good solid shape. The results show that CNT-BN-SA-1 has high latent heat, reliability, and excellent CSP energy storage capabilities. It has great application potential in the field of FSPCMs. This method provides a certain reference for the preparation of phase change composites.