In this paper, the effect of electroplsing treatment (EPT) on the microstructure evolution and the mechanical properties was studied. The recrystallization of the deformed AZ31 magnesium alloy was accelerated by using EPT with high current density and low duty ratio. EPT with different parameters was analized. The thermal and athermal effect of EPT is researched and the mechanism of the recrystallization under EPT was also revealed. The results indicated that the deformed AZ31 magnesium alloy recrystallized under the EPT for 5.5 minutes. After EPT with a pluse-width of 20 μs, a current density of 3.508×109 A/m2, a duty ratio of 0.002 and a processing time of 5min, the average grain size of AZ31 alloy is refined from 72 μm to 2 μm, the tensile strength is 295 MPa, and the elongation is 20%.