To evaluate the health status of air-to-air missile, topological structure model of Bayesian network is established based on testing theory and missile structure. According to root inputs and condition probability table, GeNIe2.0 begins to reason according to indexes, and gets the probabilities in different health statuses. The simulation result agrees to the real health status of missile. Sensitivity analysis determines the importance of missile parts, and it helps to put forward suggestions during the life circle. The health evaluation model can help to make decisions on maintenance according to the simulation result, and make it possible for basic units to take on reliability analysis.