The invention provides an excitation fault fault-tolerant power generation system of a double-salient electro-magnetic motor and a control method of the system. According to the control method, when the system detects an excitation fault, an excitation circuit is disconnected and a fault-tolerant mode is switched to for operation, and in the fault-tolerant operation mode, a fault-tolerant power generation function of the excitation fault of the motor is achieved through a novel six-beat power generation control strategy that positive-direction exciting current and negative-direction exciting current are led to each phase of a three-phase four-arm convertor. The control method of the system makes full use of the three-phase four-arm convertor of the double-salient electro-magnetic motor, enables the motor to continue to generate power under the conditions of faults, is suitable for brake feedback motors, starter generators and other multi-quadrant operation double-salient electro-magnetic motors in the aerospace industry, automobile industry and other industries.