The invention provides a method for quickly detecting the linear axis rotation angle error of a numerical control machine tool, and relates to the technical field of numerical control machine tool detection. The method comprises the steps that a measuring device is arranged on a linear axis, and an initial rotation angle error generated by installation is determined through an accelerometer; the linear axis moves at three different speeds at a constant speed, and an upper measurement system automatically carries out multi-channel acquisition and stores the measurement data of a motion measurement point; the Kalman filter principle is used to fuse rotation angle information measured by the accelerometer and a gyroscope to acquire angle errors measured at three speeds; on the basis that thesame geometric error signal can be decomposed into different frequency components, the angle errors measured at different measurement speeds are filtered; and finally, the filtered angle errors measured at three measurement speeds are superimposed to complete quick measurement of the linear axis angle error of the machine tool. The method provided by the invention has the advantages of high measurement efficiency, strong data processing capability, simple operation, high equipment integration and easy automation, and can realize quick measurement of the linear motion axis rotation angle errorof the machine tool.