Abstract: To improve the corrosion resistance of AM60 magnesium alloy, Cr coating of the alloy was prepared by mechanical alloying. The microstructure, microhardness and corrosion resistance of AM60 magnesium alloy surface were analyzed by means of XRD, video microscopy, SEM, microhardness tester and an electrochemical workstation. The results showed that Cr coating with density was successfully prepared. There was a good interface bonding between Cr coating and AM60 magnesium alloy. Meanwhile, the microhardness of Cr coating reached to 1132HV, which was 1.96 times higher than that of the substrate. When the ball-to-material ratio is 15∶1 and 20∶1, and the ball milling time is 20h and 15h respectively, which the corresponding self-corrosion current density was all 3 order of magnitudes and the corresponding corrosion voltage was increased by 55% and 238%, respectively. Impedance value were all bigger than that of the substrate. The corrosion resistance of AM60 magnesium alloy in the simulated seawater was greatly improved; Under the experimental conditions, the optimal preparation parameter of Cr coating is as follows: the ball-to-material ratio is 10∶1 and milling time is 20h, resulting in obtaining the Cr coating with the best performance.