分析了空间电离辐射的位移损伤效应影响下InGaAs PIN光探测器暗电流的损伤特性，在此基础上建立了强度调制直接检测模式的卫星光通信系统误码率模型。仿真结果表明：暗电流与辐照注量近似呈对数线性变化；误码率在辐照注量小于108cm-2时维持在10-9之下，当辐照注量大于108cm-2后加速上升。结合仿真结果，讨论了判决阈值对误码率的影响，得出在辐照强度为10-9cm-2时，若判决阈值取5.7×10-7A，则误码率降低约4个量级，较好地提高了通信质量。

The damage characteristic of the dark current of InGaAs PIN photodetects was analyzed under the influence of displacement damage of space radiation, and based on which, the bit error rate model of optical satellite communication system in intensity modulation direct detection mode was established. The results show that radiation causes logarithmic linear increase in dark current. When the radiation dose is lower than 108cm-2, the bit error rate maintains below 10-9, and bit error rate increases accelerantly when the radiation dose is larger than 108cm-2. The influence of decision threshold on bit error rate is discussed, and it is concluded that when the radiation dose is 109cm-2, if decision threshold is 5.7×10-7A, the bit error rate will decrease about 4 orders of magnitude, which can improve the communication quality efficiently.