According to the characteristics of CINRAD / SA, SB radar receiver, this article discusses the process of the receiver test channel, the signal main channel and transmitter test signal, which is related to the echo intensity calibration. Based on years of experience in weather radar technology security, this artilce discusses in detail the fault diagnosis method of echo intensity calibration, summarizes the fault diagnosis process of echo intensity calibration, and lists three examples in which the above falut diagnosis and solution are used to exclude the fault resulting from the receiver test channel, the signal main channel and the RF leakage signal of transmitter.This articles explains the importance of the fault diagnosis in CINRAD technology support and guarantee and makes some advices about it.