Frequency source stability is an important indicator of Doppler radar. If there is frequency amplitude and phase fluctuations in the radar frequency itself, it is impossible to obtain accurately strength and velocity field information. An introduction is made to the composite methods and main signal process of CINRAD/CC frequency sources, as well as the characterization methods of frequency source stability and its relationship. The impacts of the short and longterm stability on frequency source formation are studied, and the radar repair platform is used to simulate the fault. The measures how to improve the frequency stability are discussed, aiming at the rapid judgment and repair. It is summarized by means of time domain and frequency domain, combining with practical illustrations, that the phase noise (stability) of frequency sources is the main factor influencing radar echo intensity and speed measurements in modern radar. These techniques have certain reference significance for repair and maintenance of CINRAD/CC frequency sources.