CNC machine tools (including machining centers, turning centers, EDM machines and other types of CNC machine tools) are the most important equipment in the modern mechanical processing industry. CNC machine tools have a high degree of automation and high precision, and are widely used in the processing of complex parts, high-precision parts and batch parts. Before leaving the factory, CNC machine tools must undergo three types of inspections, namely geometric accuracy, positioning accuracy and cutting accuracy. Geometric accuracy is generally detected using various measuring tools, while positioning accuracy must be detected using a laser instrument. At present, the position accuracy inspection of CNC machine tools in my country adopts the national standard "GB/T 17421.2-2000" "General Principles for Machine Tool Inspection Part 2: Determination of Positioning Accuracy and Repeatability of Positioning Numerically Controlled Axes", which is completely equivalent to the International Organization for Standardization standard "ISO230-2: 1997" "Test code for machine tools-Part2: Determination of accuracy and repeatability of positioning numerically controlled axes"