A controller for on-off switching of power supplies includes: a microprocessor, to which a memory and a power supply interface and reset circuit are connected; a communication interface converting voltage signals between the microprocessor and an RS232 interface; an on-off control circuit which is connected to the microprocessor, comprising at least one relay for controlling on-off switching of the power supplies, and an amplifying circuit for driving said relay; a feedback circuit feeding on-off states to the microprocessor; and a voltage converter providing steady voltage to the power supply interface and reset circuit, the communication interface, and the on-off control circuit. The on-off control circuit is capable of controlling a large number of power supplies, and the communication interface connects the controller to a remote console.