Aiming at spare parts ordering problem for the key equipment system which degradation state distribution function is unknown,a kind of spare parts order decision optimization method which considered withcombining offailure prediction results and spare parts ordering was presented based on failure prediction.Firstly, according to the remaining life prediction results which obtained by detecting state information, the residual life of spare parts orderingwas taken as threshold to draft spares ordering decision strategy.Then, according to the theory of renewal process, the prescriptive availabilitywas selected as constraint, the expected cost per unit time was identified asoptimization goal to establish the optimization modelwhose optimization variableswere failure prediction intervals and sparepartsordering threshold.Then, according to the theory of renewal process, the prescriptive availabilitywas selected as constraint, the expected cost per unit time was identified asoptimization goal to establish the optimization modelwhose optimization variableswere failureprediction intervals and sparepartsordering threshold.Finally, the example is given to solve simulation and optimizationof the established model to obtainthe bestfailure prediction intervals and sparepartsordering threshold, which verifies the feasibility and effectiveness of the model.