In order to improve the reliability of CNC machine tools,a reliability evaluation model based on Bayes-GO under functional structure decomposition was proposed.The product was decomposed according to the idea of function-motion-action and all meta-action units that realized the product function were obtained;the Bayes method was used to fuse the sample information and priori information of the meta-action unit,and the reliability model of the meta-action units was obtained;the FMA decomposition tree was converted into a GO diagram,and according to the GO method operator and signal flow operation rules,the reliability quantitative analysis was carried out to provide an important basis for improving the reliability of machine tool design.Taking the reliability evaluation of a domestic grinding wheel frame as an example,the rationality and feasibility of the proposed method are verified.