Due to the physical deformation and thermal deformation of CNC machine tools in the machining process,it is difficult to ensure the processed quality of the parts.Therefore,it is necessary to carry out error analysis and real-time compensation for the error sources on the moving machine tool.Laser interferometer and cue instrument were used to detect the positioning accuracy of numerical control machine tool,and the mathematical model for the detected data was established,the positioning error compensation method was determined.Taking a NC machine tool as instance,positioning accuracy detection and error compensation were done.The error compensation effect were analyzed.The results show that the method is feasible and practical,and the positioning accuracy of NC machine tool is improved significantly.