跟瞄误差会引起接收光信号的衰减。为了减小跟瞄误差对星间光通信系统的影响，在跟瞄误差存在的条件下，通过选取最优光束发散角来优化链路可靠性。偏置误差是跟瞄误差的一部分，在没有偏置误差存在的情况下获得了链路可靠性的解析表达式，通过将链路可靠性进行最大化设计，获得了最优光束发散角的解析表达式。将偏置误差也考虑进去再对链路可靠性进行最大化设计，对于给定的通信速率获得了光束发散角与跟瞄误差的最佳比值的数值解及其近似解析表达式。在星间光通信中采用所设计的最优光束发散角，可在存在跟瞄误差的情况下获得良好的系统性能。

Pointing errors can reduce the number of received signals. The influence of pointing errors on intersatellite optical communication systems is decreased by selecting an optimum laser beam divergence angle for optimizing link reliability in the presence of pointing errors. Given that bias errors are part of pointing errors, an analytic expression of link reliability is obtained in the absence of bias errors. By maximizing link reliability, an analytic expression of the optimum beam divergence angle can be obtained. Bias errors are considered in maximizing link reliability. The numerical results and analytic approximation of the optimum ratio of beam divergence angle to pointing errors for a desired bit rate are obtained. With the application of the designed optimum divergence angle for intersatellite optical communication systems, good system performance can be achieved even in the presence of pointing errors.