Thermal management system is a crucial part in electric vehicles to ensure battery safety and driving comfort. A refrigerant-based thermal management system of electric vehicles with two evaporators connected in series (series system) or in parallel (parallel system) is established. The performances of the two systems are investigated and compared. The results reveal that the optimal refrigerant charge is approximately 600 g. Additionally, there is no correlation between the optimal refrigerant charge, and in the arrangement of heat sinks or the heat loads. Under the optimal refrigerant charge, the coefficient of performance of the series system ranges from 3.47 to 4.71. The coefficient of performance of the parallel system ranges from 3.40 to 4.59, which is lower than that of the series system. Furthermore, the series system has higher exergy efficiency and better cooling performance. The heat source (cabin) with a small thermal mass placed in the rear evaporator of the series system can weaken the lag of its cooling effect. The additional serial evaporator is an alternative solution to the dual-evaporator thermal management system of electric vehicles.