Abstract: Microcomputer excitation system is an important part of generator operation control. This paper compares the NARI's SAVR2000 to the Exc 9000 microcomputer-based self-excited excitation system of Guangzhou Institute of Electrical Science. By comparative analysis of the excitation regulator power supply, real-time fault diagnosis, silicon-controlled rectifier bridge operation mode and comparison of the PT disconnection criterion, some conclusions and recommendations were advanced and a solid foundation for future operation and management was laid.