Aiming at the problem that traditional methods can not deal with intercurrent activity and dynamic action, a algorithm of complex equipment's maintainability index validation based on CPN and UML was put forward. At first, we demarcated the color class of warehouse and order-brand, held in flux and arc with happen condition, and found CPN model of complex equipment. Then, we transformed CPN model to UML model based on the mapping rule from CPN to UML. At last, we programmed to implement it. This method could deal with intercurrent activity and dynamic action of system beautifully, could implement the conversion from the model to procedure structure corking, and had good mutual ability. At last, the author validated MTTR of certain equipment. The result indicated that the apply bound is wide and the maneuverability is fine.