The electrochemical machining is aimed at the fabrication of parts of prescribed shape and dimensions by the anodic metal dissolution using tool-electrodes of various types. The task of the theory of electrochemical machining is to calculate the shape and dimensions of the workpiece depending on the shape of tool-electrode and operation conditions. In this work, a pseudotransient method of modeling, which is new for the steady-state electrochemical machining, is developed. In this method, first, the initial approximation of workpiece surface is prescribed; in the course of modeling, it shifts in the normal direction at a rate proportional to the residual of steady-state condition. The proposed method requires substantially lower computational cost than the non-steady-state method and can be used for the tool-electrodes of arbitrary shape.