Effects of Ca addition (0.3％，0.6％ and 0.9mass%) on microstructure,mechanical properties and bio-corrosion resistance of the Mg-4Zn based alloys prepared by high strain-rate rolling were investigated by OM,SEM,tensile testing and etc. Ca can refine the dynamic recrystallization grains of the as-rolled alloys,increase the content and the size of the residual second phases,and thus improve the ultimate tensile strength and yield strength. The ultimate tensile strength and the yield strength of Mg-4Zn-0.9Ca are 300MPa and 278MPa respectively,about 12.4% and 68.5% higher than Mg-4Zn. However,corrosion resistance and residual tensile strength decrease with the increasing Ca content,resulting from the higher content and the bigger size of the residual second phases. The bio-corrosion of the Mg-4Zn alloy is uniform since the second phase particles are fine and homogenously distributed. The average corrosion rate immersed in 0.9% NaCl for 7 days is 0.80 mg/（cm2·d）and the residual tensile strength immersed in 0.9% NaCl for 7 and 15 days are 217 MPa and 205 MPa,respectively.