In this research we simulated ZK60 magnesium alloy bar in which the diameter is 45 mm with rigid viscoplastic finite element theory . The extrusion velocity is respectively 2 mm/s、3 mm/s、4 mm/s、5 mm/s in extrusion process. Then the process of metal flow in extrusion forming was observed and the variation of temperature 、the distribution of effective stress field and effective strain field in inner workpiece was obtained during the deformation course. At last we determined the best extrusion technical parame...