A novel method of electromagnetic coupling treatment (EMCT) was proposed to control the residual stress of 2A02 aluminum alloy blade forging in compressor, aiming at solving the industrial problem of machining deformation of large-size thin-wall parts due to residual stress releasing. The effects of electric and magnetic field treatment on the residual stress and mechanical properties of forgings were studied. The microstructure was analyzed by quasi-in-situ EBSD. The results show that compared with a single physical field, the EMCT has the most significant relaxation effect on residual stress. When the magnetic field intensity is 1.5 T and the electric field intensity is 750 V/m, the maximum reduction of residual stress of blade forging is 53%. EMCT can improve the plasticity of aluminum alloy without damaging the strength. Under the above parameters, the elongation is increased by 14.3% and the resistance is decreased by 4.9%. EBSD quasi-in-situ analysis shows that after EMCT, the geometric dislocation density of forgings is reduced by 58.2%, the small-angle grain boundaries are reduced, the plug dislocations are dispersed and annihilated, the local strain is reduced, and the macroscopic stress is relaxed.