为了解决氧碘化学激光器通过常规诊断故障定位困难的问题，采用建立的氧碘化学激光器功率失常故障树模型，结合氧碘化学激光器常用的8个监测参数：碘腔压力、碘文氏管压力、p-t曲线、主氦压力、氯气压力、氧发生器压力、上游压力和光腔压力，提出采用故障树和在线监测参数相结合的办法，基于3σ法则的判断标准对氧碘化学激光器进行故障诊断，故障诊断正确率达到94.5%，并对出现的故障提出了改进措施。

It is difficult to find out fault chemical oxygen iodine laser (COIL) because of it’s complex structure and interactions between the subsystems. To solve the COIL fault diagnostic problems, along with the development of integrate and practical COILs, it is required for keeping the device performance and reducing the maintenance cost and human resource input. Fault analysis of COILs has been done based on the fault tree analysis method. The fault tree of a COIL was established combining with on-line monitoring parameters: iodine cavity pressure, iodine venturi pressure, p-t curve, main helium pressure, chlorine pressure, single oxygen generator pressure, upstream pressure, optical cavity pressure. According to the 3σ rule, the accuracy of fault diagnosis for the COIL is 94.5%. Furthermore, improvement put suggestions has been forward.