Abstract: In this paper,the effect of antenna mutual coupling is analyzed using Z-parameter method.A mutual coupling model for synthetic aperture microwave radiometer is established based on the principle of synthetic aperture microwave imaging.Using the proposed model,we give thorough theoretical analysis for the brightness temperature retrieval distortion due to mutual coupling and its calibration method.We also give a method to reduce mutual coupling effect by optimizing antenna matching network.Simulation results show the effectiveness of the proposed mutual coupling model and calibration method,and clearly show the inversion error due to mutual coupling.