Abstract: It's a powerful means for C-Band SAR applied to oceanic monitoring. The active phase array based on T/R modules has high reliability and becomes a research hotspot. Due to the satellite SAR application, the T/ R module is required for high-efficiency, low-loss, low-mass, low-cost, high amplitude and phase stability and high reliability. In this paper, a four-channels C-band T/ R module with MMCM technology has been developed for satellite SAR application. The T/ R module channel spacing is 1/4l, in its working band, the T/ R module provides over 22W output power,23dB receive gain and 2. 3dB noise figure, over 23% power added efficiency, weight only 200g.