Abstract: Reciprocating extrusion for different passes was carried out for industrial pure magnesiums at 150, 175, 200, 225, 250 ℃. The effects of extrusion temperature and passes on grain refinement were studied by optical microscopy. The results show that the minimum temperature for reciprocating extrusion of industrial pure magnesium was 150 ℃. With the increase of extrusion temperature, the plasticity of industrial pure magnesium increased and the extrusion stress decreased, but the grain refinement effect became worse. With the increase of the extrusion passes, the grain size was refined further. The best extrusion temperature was 200 ℃, and the optimal extrusion passes was 4.