Magnesium rob is widely used in automotive hubs and cylinders due to its high strength and wear resistance.In order to improve the mechanical properties of Mg-5Sn-Si magnesium rob,the structure and mechanical properties of Mg-5Sn-1Si magnesium rob for reciprocating extrusion at 400℃were analyzed.The results show that the grain size decreases significantly after reciprocating extrusion,and the fine grain strengthening effect is very high.After more times of extrusion,Mg2Sn particles are broken to form smaller particles after being subjected to stress.Compared with the single-direction positive extrusion,the plasticity is obviously strengthened.A large number of small dimples are produced in the extensional fracture area,which can greatly improve the mechanical strength of magnesium rob.This research is helpful to improve the mechanical properties of magnesium rob and has a high application width.