The invention discloses a switch magnetic resistance generator system capable of realizing rapid excitation / demagnetization. The system comprises a switch magnetic resistance motor body, a prime mover, a position sensor, a power converter, a DC power supply and a controller, wherein the power converter is a four-level power converter. By adopting the four-level power converter, at an excitation stage, in an angle position control mode, the exciter current of a phase winding is increased, and the energy storage of a magnetic field is increased so that the output power of an overall power generation system is improved and it is easier for the power generation system to reach a rated power; in an current chopping control mode, the excitation time is reduced, rapid excitation is realized, and the time of a generating stage is increased so that the generating capacity of a motor is enhanced and the output power of the system is increased; and at the generating system, when two voltage sources are utilized, rapid demagnetization can be realized.