The present application provides a method for controlling a power-down detection circuit, a controller and a computer readable storage medium. The method includes: receiving, by a controller of a power-down detection circuit, a power-down signal, wherein the power-down signal is sent from a power-down detection sub-circuit of the power-down detection circuit when it is determined by the power-down detection sub-circuit that an output voltage of a low-voltage side power supply of the power-down detection circuit is smaller than a threshold, and wherein the power-down detection sub-circuit and the controller are powered by the low-voltage side power supply; controlling, by the controller, a memory of the power-down detection circuit to record fault information, wherein the fault information comprises current information of a high voltage bus sensed by a high-voltage side current sensor of the power-down detection circuit; and performing, by the controller, a fault diagnosis based on the fault information.