With the increasing requirements of the high-speed CNC machine tools for the motion accuracy of the spindle,it is necessary to study the accuracy of the permanent magnet synchronous（ PMS） grinding motorized spindle. Based on the spindle vibration error and thermal analysis,mathematical models of radial error motion,tilt error motion and axial error motion are established. The least squares approximation algorithm is applied to fit the radial trajectory of the spindle,and then the inclination error is modeled to obtain the tilt angle of the spindle’s axis of rotation. Combined with the time domain and frequency domain signal analysis methods,the axial motion error trajectory is analyzed. To achieve a radial and axial error displacement of the spindle and obtain the spindle thermal error,a typical double standard ball 5-DOF measuring spindle error device is used.Experiments were carried out on the spindle rotation error during the test run by the PMS motorized spindle developed by a domestic machine tool factory. The results show that when the speed increases to the maximum speed,the radial error and the axial error increase,the centrifugal force has a more obvious effect on the spindle accuracy; when there is the spindle eccentricity,the radial error motion trajectory gradually transitions from the approximate circle to the petal state. The double standard ball five-point test method can not only judge the manufacturing,assembly and other problems of the electric spindle manufacturing,and the experimental method can be applied to the experiment of the electric spindle error motion,while satisfying the inclination error,the axial error motion and the spindle temperature deformation test.