In order to improve the machining accuracy of the permanent magnet synchronous spindle, reduce vibration, reduce its electromagnetic noise，considering the influence of the harmonic magnetomotive force, the analytical expression of the airgap flux density of the permanent magnet synchronous motor was derived and the calculation accuracy of the radial flux density of the permanent magnet synchronous motor was improved.Radial flux density and its harmonics were calculated by analytic method, and radial electromagnetic force was solved by finite element method.The threedimensional model of the permanent magnet synchronous spindle was established and mode analysis and harmonic response analysis were carried out. The vibration acceleration of the spindle was measured.The model electromagnetic force frequency and modal analysis results were compared with the measured vibration acceleration spectrum. The results show that the radial electromagnetic force is the main cause of vibration. Resonance is the main factor of noise.By optimizing the structure of the permanent magnets, the radial electromagnetic force of the permanent magnet synchronous motor spindle is reduced. The noise reduction is verified by the noise simulation analysis.