With the large latent heat and low cost, the paraffin has been widely used in battery thermal management(BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting in a cavity has been established, and the effects on the solid–liquid phase change process have been investigated for the purpose of enhancing the heat transfer performance of paraffin-based BTM system. The results showed that the location of the heating wall had great effects on the melting process. The paraffin in the cavity melted most quickly when the heating wall located at the bottom. Furthermore, the effects of thermal conductivity and the velocity of the slip wall have been considered. The gradient of liquid fraction increased with the increase in thermal conductivity, and the melting process could be accelerated or delayed by the slip wall with different velocity. With the large latent heat and low cost, the paraffin has been widely used in battery thermal management (BTM) system to improve the efficiency and cycling life of power battery. The numerical model of paraffin melting in a cavity has been established, and the effects on the solid-liquid phase change process have been investigated for the purpose of enhancing the heat transfer performance of paraffin-based BTM system. The results showed that the location of the heating wall had great effects on the melting process. The paraffin in the cavity melted most quickly when the heating of wall located at the bottom..., the effects of thermal conductivity and the velocity of the slip wall have been considered. The gradient of liquid fraction increased with the increase in thermal conductivity, and the melting process could be accelerated or delayed by the slip wall with different velocity.