Abstract: Unit 4 of a certain thermal power plant adopts the QFSN-630-2YHG type steam turbine generator produced by Harbin Electric Power Plant, with an excitation system of self parallel excitation at the machine end. The microcomputer excitation regulator is the NES6100 digital excitation regulator produced by Nanrui Electric Control Company. This article describes the parameter optimization work of the excitation system of Unit 4. The optimization results of the excitation system parameters of Unit 4 are given, and the Pressure regulator model and parameters of PSASP simulation analysis program are provided. Based on the actual application database of the PSASP simulation analysis program, the simulation verification was carried out, which was consistent with the experimental results. The model and parameters can be directly applied to the PSASP simulation analysis program. This research and application has great reference significance for similar excitation system parameter optimization projects and has promotion value。