In this paper, three kinds of low alloyed Mg-Zn-Y (Mg-0.6Zn-0.1Y, Mg-1.3Zn-0.1Y, Mg-2.0Zn-0.1Y, wt.%) were prepared by conventional casting and then subjected to slow extrusion at low temperature (140°C, 0.1 mm/s). The results showed that with the increase of Zn content, the grain size of the alloy before extrusion gradually decreased. After extrusion, the grains were significantly refined and dispersed nano-precipitated phases were form. At the same time, as the increasing the Zn content, the recrystallization degree of the alloy and the number of nano-precipitation increased, while the basal texture intensity exhibited unobvious change. The mechanical properties of the as-extruded alloys have been dramatically improved. The YS,UTS and ELof Mg-2.0Zn-0.1Y alloy were 406.4MPa, 424.5MPa and 12.2%, respectively. With the increase of Zn content, the elongation of Mg-Zn-Y alloy increased significantly, the fracture morphology changed from cleavage surface to tiny dimples, and the fracture pattern varied from cleavage fracture to ductile fracture.