In order to solve the problem of positioning accuracy stability between blade and shank for automatic tool welding process,the quick verification of lead screw was carried out by means of metrological evaluation method.On one hand,a three-layer topology network was established composed of personal computer,programmable controller and lead screw; on the other hand,the sequential function chart was used as a tool to clearly describe the logical process of length verification.Then,under the automatic control of the program,the data acquisition,numerical processing and later graphic analysis for the walking lead screw were performed.Finally,the initial positioning accuracy,the repeated positioning accuracy and positioning system deviation were reasonably obtained according to the above information.The debugging results show that the regular or random metrological verification for equipment related to precise length measurement is of great significant to improve the internal quality control index of products for manufacturer.