In order to extend the cycle life of power battery pack within electric vehicle, a phase change material (PCM)/mini-channel coupled power battery thermal management (BTM) system, as well as the three-dimensional battery thermal model, was designed in this paper. The effect of various influencing factors, especially mass flow rate of water, phase change temperature and thermal conductivity of PCM, were investigated numerically. The results showed that the liquid volume fraction of PCM was greatly influenced by the thermal conductivity and the phase change temperature of PCM. The increasing number of channels results in a decrease of the maximum temperature (T Max) and maximum temperature difference (ΔT) of battery packs. The optimal phase change temperature and thermal conductivity of PCM were 308.15K and 0.6Wm−1 K−1 respectively when the number of channel was eight and the mass flow rate was 8×10−4 kgs−1. Moreover, a maximum temperature of 320.6K was predicted for the PCM/mini-channel coupled BTM system, while a maximum temperature of 335.4K was predicted for the PCM-based BTM system. Additionally, the PCM/mini-channel coupled BTM system presented more effective thermal performance and the research will be a clear indicator for the design of the PCM/liquid coupled BTM system.