Abstract: Multi-axis linkage accuracy is the core index to evaluate the performance of machine tools. This paper proposes a fast detection method for the accuracy of CNC machine tools based on built-in sensors, aiming at solving the problems of long occupancy time, low frequency, offline detection in traditional CNC machine tool multi-axis linkage accuracy detection methods. Firstly, the error model of the machine tool is established, and then the position data such as the interpolator, encoder, and grating ruler of each axis are collected based on the CNC machine tool servo control principle, and the position data is input into the error model to obtain the tool center point value, such that the multi-axis linkage accuracy of the machine tool can be obtained. Finally, the validity of the proposed method is verified by detecting the contour accuracy an S test piece which is machined by the machine tool. The proposed method can provide an important way for rapid detection of multi-axis linkage accuracy of the machine tool.