Taking the domestic CNC machine tools as the research object, the reliability evaluation of NC machine tools was carried out by using the user site reliability timing truncation test method,based on the collected reliability test data. The process and method of reliability evaluation for machine tool users was elaborated: Firstly, the appropriate reliability model was chosen; Secondly, the estimation method of the model parameters was selected; Finally, the goodness of fit test was completed according to the selected model and parameter estimation results.Combined with the process, the specific example was given, and the reliability of the machine tool was evaluated without considering the difference of the operating conditions, and the reliability level of the machine tool was obtained.