The current maintenance support situation of the newgeneration weather radar in China at present is introduced. The radar fault diagnose system is used to assist and replace the traditional radar fault diagnose means, which can shorten the time for maintaining radar faults, standardize the radar maintenance means, and improve the efficiency of radar maintaining. Taking the CINRAD/SA weather radar as an example, through a detailed study of the CINRAD/SA weather radar system, in combination with the radar fault location function, the collection method of radar fault messages is determined. About 70 relatively complete cases of CINRAD/SA radar fault maintenance from 2002 to 2014 are collected and analyzed. Based on the Fault Tree Analysis (FTA), the radar fault tree is developed. The radar transmitter is taken as an example to make the qualitative and quantitative analysis of the fault tree, and the initial data are obtained. Based on the analysis, the CINRAD/SA Weather Radar Fault Diagnosis System is developed, which provides guidance for radar fault diagnosis.