Abstract: To improve the radiation immunity of the charge coupled device (CCD) in satellite optical communication system, the ionization damage and displacement damage effects imposed on CCD in space radiation environment were analyzed. Through theoretical analysis and numerical calculation, the influences of radiation source, buried channel and bias on the charge transfer efficiency (CTE) of CCD were researched. The results show that the space radiation mainly affects the performance of CCD with the bulk dark current density and CTE. The CCD used in satellite optical communication system should be selected as the P channel CCD and set as under unbiased state when the communication system is not working.