CNC cylindrical grinding machine reliability is an important performance indicators, the level of reliability will directly affect the use of CNC cylindrical grinding machine. Reliability of the traditional classification method is not clear, standards are not uniform, the paper application taxonomy for 12 CNC grinding machines from September 2012 to July 2014 for two years more than 600 pieces complete failure and repair data for statistical analysis to identify a greater impact on the overall reliability of the fault location and cause of the malfunction. According to the probability of occurrence of each failure mode, the severity of harm's comprehensive evaluation of the degree of fault of each site, identify the weak links of the whole system. As a result, the reliability of CNC cylindrical grinding machine will be greatly improved.