Laser electrochemical compound etching, combining laser energy and electrochemical etching processing, removes the workpiece material by using the thermal-mechanical effect of laser and electrode reaction, and achieves the selective localized etching processing. For the multiple-field coupling characteristics of laser electrochemical compound processing, the finite element analysis software ANSYS is used to perform finite element numerical simulation of transient temperature field and electric field of the compound etching target material. The influence of changes in the transient temperature field and electric field on the scope and depth of processing area is studied. By comparing the results with experimental ones, the laser electrochemical mechanism of material removal and etching forming is shown. The surface topography characteristic of the micro-machining process in laser electrochemical compound processing is discussed, which provides the guidance for the optimization of compound processing technology.