A new severe plastic deformation for manufacturing thin-walled tube made of AZ31 magnesium alloy called TEB(Tube-Extrusion-Bending ) process, which combines direct extrusion with two step bending,has been developed to manufacture tube.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 containers and dies 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 evolution. The results showed that refined and uniform microstructures can be achieved by TEB process. The research results showed that the TEB process would produce the serve plastic deformation and improve the recrystallization of the grains.The comparisons of FEM simulation and experimental results have been made to obtain the relative important principles of TEB process.