The present invention discloses an automobile self-regulating excitation power generation system, comprising a rectifier, a storage battery and an electrical device, and further comprising a power generation system and an excitation system. The power generation system comprises a synchronous generator, of which the power output end is connected with the alternating-current end of the rectifier. The synchronous generator comprises a stator comprising a stator winding and a rotor comprising a rotor excitation winding. The excitation system comprises an exciter and an excitation adjustment mechanism. The excitation adjustment mechanism comprises a sliding resistor throttle position sensor and a throttle shaft, and the sliding resistor throttle position sensor comprises a power terminal, a grounding terminal and a sliding contact linked with the throttle shaft. The automobile self-regulating excitation power generation system can output stable current to power the storage battery and the electrical device regardless of the rotate speed of the engine, thereby effectively preventing power supply failure on the storage battery and the electrical device when the rotate speed of the engineis too low, and avoiding damage to the storage battery and the electrical device when the rotate speed of the engine is too high.