The corrosion resistance of Ag ion implanted with dose of 1.5×1017 cm-2 for Mg-1.0 Ca-0.3 Zn magnesium alloy in the simulated body fluid was investigated. The surface hardness and elastic modulus of the alloy and the polarization curve in the SBF were obtained by Nano Snick and three electrode system, respectively. The results indicate that the hardness and the elastic modulus are improved obviously after the implantation of Ag ions, the surface hardness reaches the maximum at a depth of 250 nm below the alloy surface. Meanwhile, the polarization resistance is strengthened, and consequently the corrosion resistance of the alloy is improved. Moreover, the pH value of the SBF within 48 h increases gradually and the alkalization of the SBF is accelerated.