At present, the development of through-mask micro-electrochemical machining is only limited to static machining, where the size of the tool is usually the same as that of the workpiece. However, in the electrochemical processing, metal with good electrical conductivity is chosen as the tool electrode, and it is usually very expensive. Based on the cost consideration, a moving tool with small size may be preferred. Finite element method is used in this paper to create the electric field model of through-mask micro-electrochemical machining with moving tool. The effects of the parameters, such as applied voltage, mask thickness, on the machining shape are investigated. The results show that the higher the applied voltage, the larger the machining depth and width, and also the better the aspect ratio. When the thickness of the mask is thin, the electric field is unevenly distributed and the lateral corrosion is more serious. There is an island-like phenomenon, which is related to the masking of the mask. When the moving speed is relatively slow, the relative processing time is longer. The current density accumulated on the surface of the workpiece is thus higher and the material removal rate is higher. As the processing time increases, the machining depth becomes deeper, and the forward corrosion rate is slow down.