A thermostatic assembly for power members of an electric vehicle includes a pipe set having a main pipe and a recycle pipe, one end of the main pipe connected to one side of the pump, a plurality of temperature-adjusting pipes connected between another end of the main pipe and one end of the recycle pipe, another end of the recycle pipe connected to another side of the pump, a plurality of power members respectively set on the temperature-adjusting pipes, a input change valve set between the main pipe and each temperature-adjusting pipe, a output change valve set between the recycle pipe and each temperature-adjusting pipe, a controller electrically connected to the input change valve, the output change valve and each power member. Under this arrangement, the controller ranks a sequence of the temperature information and defines a sequence of the flow direction of the temperature-adjusting water.