Effect of Zn on the corrosion properties of homogenized Mg-3Sn-Ca alloy was investigated in this paper. The second phase is composed of CaMgSn and Mg₂Sn in the Mg-3Sn-Ca alloy. The grains are significantly refined by the addition of Zn. The volume fraction of the second phases increase and exist dispersed distribution. Mg₂Ca phase is precipitated. In addition, the corrosion rate of Mg-3Sn-Ca(TX31)and Mg-3Sn-Ca-Zn(TXZ311)alloys were analyzed by immersion and hydrogen evolution test. The corrosion resistance of TX31 and TXZ311 alloys was analyzed by electrochemical polarization curves and impedance spectroscopy. The results show that TXZ311 alloy has smaller grain size, more uniform distribution CaMgSn phases and more dense corrosion film, which cause the higher corrosion resistance of TZX311 alloy.