The invention discloses a flexible distribution network power supply system fault control method. The fault control method comprises the steps of (1) when a wire inlet power supply fault occurs, maintaining system stability by a wire inlet power supply fault control unit in a flexible distribution network power supply system fault control unit, and controlling to realize normal power supply recovery of a power-down alternating current bus; (2) when buscouple fault occurs, maintaining system stability by a buscouple fault control unit in the flexible distribution network power supply system fault control unit, and controlling to realize normal power supply recovery of the power-down alternating current bus; and (3) when a flexible conversion system fault occurs, maintaining system stabilityby a conversion system fault control unit in the flexible distribution network power supply system fault control unit. According to the fault control method, when the wire inlet power supply fault, the buscouple fault or the flexible conversion system fault occurs, the operation states of a switch and the PCS are controlled reasonably, so that stable system operation is realized under a fault working condition; and meanwhile, when the corresponding fault is recovered, normal power supply recovery of the system can be controlled, thereby effectively improving power supply reliability and flexibility of the power supply system.