Nuclear power plant diesel generators need to have the characteristics of fast start-up speed, large active power, long power supply time, high reliability, good load performance, and so on. As the core control component of the unit, the speed regulation system plays a crucial role in the stable and reliable operation of the unit. The low frequency oscillation exists in the traditional speed regulation control method for diesel generators with external power network fluctuation. To solve the problem, a kind of speed regulation method for diesel generators based on power system stabilizer (PSS) and fuzzy PID control is proposed. The diesel generator speed control system model is built based on MATLAB Simulink simulation software. The simulation results show that the proposed method has high adaptability and robustness, which not only improves the control precision of diesel engine speed, but also speeds up the stability of terminal voltage and power.