In order to study the effects of square wave current on the electrochemical rehabilitation of concrete structures， two kinds of electric fields， i.e. constant current and square wave current， were used. The open circuit potential， liner polarization， electrochemical impedance spectroscopy， tensile test and scanning electron microscope were used to compare and analyze the influence of electric fields on the corrosion and mechanical properties of the reinforcements in mortars. The results show that the corrosion current density of reinforcement under the square wave electric current is smaller than that under the constant current electrochemical rehabilitation， while the mortar resistance， the resistance of passive film on steel and the reaction resistance are larger than those under the constant current field electrochemical rehabilitation. The electrochemical rehabilitation under the square wave electric field has a more significant effect on the cement mortar layer， enhances the stability of the passive film on reinforcement， and reduces the corrosion rate. The square wave current can reduce the influence of cathodic polarization on the plasticity of reinforcement and decrease its hydrogen embrittlement.