Under the action of loading, environments and interior factors of materials, the performance of civil engineering structures will deteriorate gradually.Appropriate health monitoring and damage detection is of great significance to ensure the structural safety and reliability.This paper proposes a time variant structural reliability model based on degradation rule of structural components.On this basis, a life cycle cost model of the structure including maintenance costs and failure loses is established, and the optimum maintenance strategy for the structure is discussed.In the reliability model, resistance and loads are modeled as two different stochastic processes, and both stationary load and impulse load are taken into consideration.Then according to the prediction model, the state of structure is divided into a, b, c, d four levels, which is used to describe the structural performance degradation, and build a life cycle cost model based on which the overall cost is minimized through proper maintenance strategy.The proposed model will be validated through examples such as multi-storey buildings and bridge structures.