Abstract The dosage of phase change material (PCM) used is a core parameter of the PCM-based thermal management module. In this paper, a PCM-based thermal management module is built, then its numerical model is established and validated by experimental data. To accurately evaluate the influence of PCM dosage on battery temperature, a parameter called “heat ratio” is proposed. The detailed parametric study of the PCM dosage and its effect coupled with the phase transition temperature, the thermal conductivity of PCM, and the heat transfer coefficient are systematically conducted under a single discharge process and discharge-charge cycle conditions. The results indicate that the “heat ratio” between 0.75 and 1 is relatively suitable for controlling the battery temperature in a single discharge process. Higher thermal conductivity of PCM is beneficial for improving the performance of cooling system as well as the utilization of PCM, and increasing the heat ratio of PCM can further reduce the temperature of the battery once the thermal conductivity reaches a threshold. The “heat ratio” bigger than 0.75 can guarantee the PCM with lower phase transition temperature exerts its advantage in controlling the operating temperature of battery in the case of short-term operation. On the other hand, under extreme working conditions or long-term operating cycles, a higher phase transition temperature will bring a better cooling performance. However, merely increasing the dosage of PCM is not feasible. To achieve a more stable and low power cooling effect, it is more effective to combine the passive and positive cooling strategy which has a reasonable convective heat transfer coefficient.