For the torque performance degradation caused by flux leakage in interior permanent magnet synchronous motors, a synergistic optimization method integrating air magnetic barrier design and non-uniform air gap was proposed. Based on the magnetic circuit analysis method, a mathematical model of flux leakage was established to uncover the coupling mechanism between the geometric parameters of the magnetic bridge and the slot gap of permanent magnets. Firstly,a stepped air magnetic barrier topology was designed. Key design variables were screened via the adaptive metaheuristic optimization prognosis model for parameter analysis, enabling reconstruction of flux leakage paths. Post-optimization, the output torque increases by 2.95%, and torque ripple decreases by 6.92%. Subsequently, a nonlinear uneven air-gap compensation strategy was proposed. Combined with the AMOP adaptive metamodel of opitimal prognosis algorithm, a Pareto front solution set was established to achieve air-gap flux density harmonic suppression. After secondary optimization, the output torque reaches 134.59 N·m, achieving an 11.94% improvement under actual operating conditions. The results demonstrate that this synergistic optimization scheme effectively reduces flux leakage, significantly enhances output torque, and improves overall motor performance.