Through statistical analysis of the new generation weather radar faults in Guizhou in 2018, CINRAD/CD radar servo system faults accounted for 37% of the total faults, and some servo system faults took longer to eliminate. Due to the variety of servo system failures, mastering the signal flow of the servo system is the fundamental method to solve the fault. Therefore, this paper first introduces the CINRAD/CD radar servo system principle and signal flow. Then, the fault diagnosis step and process of the servo system are given according to the servo system signal flow. Finally, the station personnel are required to do routine maintenance and calibration, which can avoid some soft faults such as looseness and disconnection. Effectively improve CINRAD/CD radar servo system troubleshooting efficiency and service availability.