The thermal management system for electric vehicles is developed. Called the Thermal Link System, it consists of a heat-pump air conditioner, a system recovering waste heat from the electric power train, and a heat exchanger between the air-conditioner refrigerant and the power-train coolant water. The recovered heat is used for interior heating, so the amount of power consumed by the heat-pump air conditioner can be reduced. In this system the refrigerant for the heat-pump air conditioner and the coolant water for electric power trains are thermally linked by the heat exchanger, which can reduce the temperature of the coolant water to less than that of the surrounding air. This enhanced cooling function increases the power of electric power trains, or extends the amount of time at full power operation. Here we describe the Thermal Link System's mechanism and effects on energy efficiency.