Entropy weight comprehensive optimum seeking method is one of the optimization methods of reliability evaluation model. In the optimization process, several empirical models and multiple evaluation indexes were proposed for selecting a best model of reliability evaluation models. Entropy weight is defined to show the importance of evaluation indexes simultaneously. In this paper, an application case of CNC grinding machines was used to describe the optimization method in detail. The analysis result showed that the optimal reliability distribution model of CNC grinder is the mixed welbull distribution, and the method is reasonable and effective.