Abstract: AM80 magnesium alloy hot extrusion limit diagram was constructed by calculations, and the process parameters were chosen according to this limit diagram. Then using a combination of simulation and experimental methods, the effects of extrusion temperature and rate on the variation of extrusion pressure and exit temperature were studied in the process of AM80 magnesium alloy extrusion, and the optimal process parameters were obtained. The results show that the best extrusion process parameters were extrusion temperature of 350 ℃ and extrusion rate of 3 mm·s-1. It was found that finite element simulation could reflect the effects of different magnesium alloy extrusion parameters on the deformation. By verification of extrusion sheet surface quality, the experimental results agreed well with the constructed extrusion limit diagram.