[Objective] Harmonic current injection is an effective approach for suppressing electromagnetic vibration and noise in permanent magnet synchronous motor (PMSM). However, traditional methods face difficulties in determining the parameters of harmonic currents and neglect the coupling between the radial electromagnetic force and torque. [Methods] Firstly, a 10-pole 60-slot PMSM was taken as the research object in this paper. Considering the slotting effect, the dominant electromagnetic force component was identified as the 0-order 12-time frequency through two-dimensional fast Fourier transform, and its sources were analyzed. Subsequently, the coupling mechanism between harmonic currents and radial electromagnetic forces was analyzed. To address the strong interaction between harmonic currents and electromagnetic performance, a multi-objective optimization model was formulated that considers vibration suppression and torque performance. The amplitudes and phases of the harmonic currents were optimized using multi-objective genetic algorithm (MOGA). Finally, a multi-physics simulation model incorporating electromagnetic-structural coupling was developed to validate the vibration responses of the motor. [Results] The results demonstrated that the armature reaction slot harmonics and permanent magnet field interactions were the dominant contributors to radial electromagnetic forces. Further experimental verification showed that injecting harmonic currents with MOGA-optimized amplitudes and phases achieved a 12.75% reduction in motor vibration acceleration and a 2.61% decrease in torque ripple. These improvements validated both the effectiveness of the optimization algorithm and the feasibility of the harmonic current injection strategy for vibration suppression. [Conclusion] The MOGA-based harmonic current parameter optimization method proposed in this paper achieves an effective trade-off between vibration suppression and torque performance enhancement, providing both theoretical insights and practical references for electromagnetic force mechanism analysis and active suppression strategies.