<p>The permanent magnet generator with motion rectifier (MR-PMG) can harvest energy from reciprocating motion, and it has broad application prospects in field of wave energy generation. In the process of bi-directional input, radial electromagnetic force has significant impact on vibration of the generator. This paper focuses on radial electromagnetic force and electromagnetic vibration of MR-PMG. Firstly, the air gap flux density and radial electromagnetic force of the MR-PMG are calculated, and finite element method is used to analyze time-space and spectral characteristics of the radial electromagnetic force. Secondly, the natural frequencies of each vibration mode are calculated using modal superposition method and the influence of radial electromagnetic force on generator vibration is obtained by magnetic-structural coupling analysis. Finally, the influence of structural parameters on low-order radial electromagnetic force is discussed. The research results indicate that the generator does not resonance at low speed, and the twice frequency of radial electromagnetic force has the greatest impact on electromagnetic vibration. The radial electromagnetic force of MR-PMG can be reduced by increasing slot notch width, air gap length and polar arc coefficient while reducing the thickness of permanent magnet. The research results can provide theoretical basis for further research on vibration suppression and structural optimization of MR-PMG.</p>