After making qualitative and quatitative calculation with the Smedleys method, we determine the reliability ratio of the system, find out the key components, and thus point out a way to improve the reliability of the system. 利用西门德勒斯法进行定性分析与定量计算,确定了整机可靠度,找出了系统的关键零部件,为提高系统可靠性提供了改进的途径。