Abstract: In HF Ground Wave Radar (GWR), the DOA of signal is detected by MUSIC algorithm in spatial spectrum estimation. The mutual coupling of arrays and the inconsistencies of amplitude-phase characteristics of receiving channels has a direct influence on the resolution, precision and stability of DOA. In this paper, a method for calibration of radar arrays and channels based on sea echo is developed. It considers both the mutual coupling of arrays and the inconsistencies of channels and does not need any auxiliary signal source, the compensation of amplitude-phase characteristics of receiving channels and the DOA estimates can be obtained from the received sea echo data by means of global optimization. The method has been proved to be feasible by the computer simulations with the experimental data of the radar station in Longhai, Fujian China.