The electrochemical process and surface layer composition on steel surface under the conditions of cathodic polarization were studied. The electrochemical methods and surface analysis methods for steel were used to investigate the possibility that rust layer was reduced in alkaline solution. The cathodic process of rust in the alkaline environment was studied by powder microelectrode. The results show that the electrode process of steel and oxide layer in the alkaline environment shows obvious redox reaction. The anodic process of rust shows two phases, but that of steel shows three stages. Different degrees of reduction occur to rust by electrochemical realkalization, while its volume would be reduced accordingly. Ecorr is made further substantial increase by electrochemical realkalization, but the corrosion current density does not reduce significantly.