The invention relates to a heat radiation device, and particularly to a heat radiation device of an electric vehicle controller. The heat radiation device comprises the components of a Stirling engine which has a heat absorption head; a pipeline into which fluid is input, wherein the pipeline comprises a first loop and a second loop, the first loop is configured in a heat concentration area, and the second loop is configured in a heat concentration area and a heat edge area, and furthermore the first loop and the second loop are in heat conduction contact with the heat absorption head; a temperature sensor which is used for detecting a temperature signal in the heat concentration area and outputting the temperature signal; and a three-way solenoid valve which is connected with the first loop, the second loop and the temperature sensor and is used for receiving the temperature signal and switching the first loop and the second loop. The heat radiation device can realize heat radiation loop selection according to the temperature condition of the controller, thereby realizing a heat radiation effect and furthermore realizing an energy-saving effect.