The limit improvement factor of CINRAD/SA transmitter, which is the abbreviation of SA model of China New Generation Radar, is including two parts of transmitter input and output limit improvement factors. It can affect the spectrum estimation of radar echo signal and the filtering capabilities. In order to analyze and diagnose for abnormal limit improvement factor of CINRAD/SA transmitter, we introduce its principle firstly in this paper, elaborate mathematical model of minimum cut sets method, combining with the signal power and pulse envelope, then analyze the transmitter and receiver circuits which can impact the limit improvement factor, and last classify the disturbance causes of different frequency. We can find the causes for interring and provide relevant solutions in this way, give better advice and assist for radar technologists to complete test on site and the work of maintenance and service, ensure CINRAD/SA running smoothly.