The invention relates to a method for achieving process optimization by simulating magnesium alloy equal channel angular extrusion. The method is a numerical simulation study method conducted based on magnesium alloy compressional deformation, crack initiation and extension in the magnesium alloy equal channel angular extruding process can be effectively simulated, cracks generated in the magnesium alloy equal channel angular extruding process can be well predicted, and correctness for predicting the equal channel angular extruding crack initiation and extension of damage prediction calculation procedures is verified. By the adoption of the method, ruptures of a metal material in the equal channel angular extruding process can be predicted, and a theoretical foundation is provided for process optimization.