Abstract: A power supply apparatus includes a case, a circuit board, at least one heating element, and at least one internal liquid cooling heat-dissipation structure. The heating element is disposed in the case and electrically connected to the circuit board. The internal liquid cooling heat-dissipation structure is disposed in the case and located in at least one of manners which include being located between the case and the circuit board and being located between the case and the heating element. The internal liquid cooling heat-dissipation structure includes a tank and a heat conducting sheet. The tank includes an internal pipe. A working fluid is adapted to be filled in the internal pipe. The heat conducting sheet is assembled to the tank. The heat generated by the heat element is transmitted to the tank through the heat conducting sheet and dissipated by the working fluid circulating in the internal pipe.