Abstract: In order to improve the positioning accuracy of NC machine tool, the error source of machine tool precision should be analyzed and compensated. The principle of precision detection and compensation of numerical control machine tool based on linear regression theory with laser interferometer is discussed. The model of data detection is established. The characteristics of each error point are analyzed. The methods of one-time linear compensation and multistage linear compensation are determined and verified by comparison. Based on the analysis of a numerical control machine tool, the error compensation is realized according to the experimental data. Finally, the compensation effect of positioning accuracy is analyzed. The results show that the accuracy of X axis is increased from 4.853 1 ~35.025 0μm to -2.472 1 ~0.736 3 μm by linear compensation. The precision of Y-axis was improved from -14.425 0 ~-4.132 5μm to -2.481 2 ~0.752 9μm. The accuracy of Z-axis was improved from -4.128 0 ~17.227 1μm to -0.501 5~1.324 5μm. The precision of X axis was improved to -1.364 1 ~0.484 0μm by multi-stage linear compensation. The precision of Y-axis was improved to -1.364 1 ~0.551 0μm. The accuracy of Z-axis is improved to -0.412 0 ~0.495 2μm. Before compensation, according to the main characteristics of data distribution, the linear or segmented compensation for the system error of CNC machine tools has a good compensation effect.