It is of great significance to measure the roundness of the tool rest hole of five-axis CNC machine tool,and the roundness of the tool rest hole has a decisive influence on the subsequent batch production.In order to evaluate the hole roundness of some five-axis CNC machine tool holder more scientifically and reasonably,the CMM was used to measure the hole roundness of the five-axis CNC machine tool holder,and the evaluation method of the uncertainty of the measurement results was studied.The sample tool holder was repeatedly measured by CMM to obtain the roundness measurement feature data of the tool holder,and the measurement data were combined with the uncertainty evaluation model for calculation and evaluation analysis.Finally,the evaluation results were compared and matched with the current norms and standards to verify its rationality and correctness.The results show that the method is reliable.