The linear axis of the machine tool needs to be online detected to provide the realtime feedback parameter information of the system operation,which can be used to infer and predict the performance of the machine tool.The use of inertial measurement units (IMUs) has considerable research value for online condition monitoring.A method based on spatial filter was proposed.The wear condition of the linear guide was determined by using IMU to detect the motion error,then the variation of the translational and angular error caused by the guide wear could be solved.The precision can reach 1.5 μm and 3.0 μrad respectively.Two motion trajectories error tracking methods were mainly elaborated.The first was to determine the guide position caused error motion.The second was to determine the root cause of nonlocal damage along each guide.These methods are beneficial to the optimization development of intelligent machine tools and provide a reliable theoretical basis for the precise control of machine tools.