To explore the effects of process parameters on evolution of extrusion forces and temperatures and strains and microstructures for composite extrusion of magnesium alloy tube which includes initial direct extrusion and some steps bending processes subsequently,which is shorten for “TEB” in this paper.The TEB process has been researched by using finite element modeling (FEM) method. The rules of extrusion temperatures and the extrusion forces varying with process parameters have been developed. A TEB process with installed container and die has been constructed to perform tests in order to validate the FEM model with different process conditions. And the microstructures evolution have been researched based on effective strains development. The results showed that refined and uniform microstructures can be achieved by TEB process. The research results showed that the process would produce the serve plastic deformation and improve the recrystallization of the grains.The comparison of FEM simulation and experimental results have been made to obtain the relative important principles of TEB process.