Equal channel angular pressing (ECAP) processes have the capability to produce bulk nonstructural materials without loose holes. Using commercial metal forming finite element code, ECAP process is analyzed numerically in this paper. It is combining through node reflection method and three-dimensional model switching to realize multi-pressing process of Routs A, Ba, Bc and C by using finite element method, the distribution of accumulated effective strain and the influence rules of deformation uniformity in round billets are obtained, and the grain refine mechanism of equal channel angular multi-pressing for different processing Routes are obtained. The microstructure evolution of the workpiece can be changed via different processing routes. With increase of passes pressing, the grain microstructure in the workpiece is gradually refined for different processing routes. It is found that route Bc can get a high angle grain boundaries distribution in the workpiece than other routes. In addition, the experimental microstructure results are also consistent with FE analysis results. The microstructure evolutions of grain refinement mechanisms for different multi-pass ECAE processing routes are accord with the accumulated effective strain rules in the workpiece. Those results can offer better process planning and guidelines for ECAP experiments.