Abstract: Maintenance is a good means to retain or recover the product state. In order to understand the reliability law of products under the condition of periodic maintenance, a performance deterioration rule model is established based on the composite Poisson process. In the model, the failure mechanism and the product deterioration character are fully considered in the case of periodic maintenance. The model can be used to determine the reliability and failure rate. An analytical expression, which can specify the maintenance effect, is presented by analyzing the change law of failure rate. The model can exactly describe the reliability law of product by taking the pump rotor for example. It also can portray the maintenance effect more objectively and intuitively.

Key words: applied statistical mathematics, imperfect maintenance, state recovery, performance deterioration, recovery factor