Abstract: Based on microstructure analysis and mechanical p roperty research of the samp le ofmagnesium alloy, Mg - 6. 0Zn - 1. 2Y andMg - 6. 0Zn - 0. 6Zr - 1. 0Y, which experienced squeezing and heat treatment, this paper discussed the existence form of rare - earth element Y in ZK60 alloy and the influence of its actingmechanism onmicrostructure and mechanical p roperty of this alloy. The result shows that rare - earth element Y can make grain refinement and crystal boundary refinement of ZK60 magnesium alloy and that, when the amount of added rare - earth element Y is 1. 0% wt, a lof of Y and Zn are enriched at crystal boundary, Y - Zn phase grain becomes larger, as a result, the intensity of the alloy decreases and the extensibility increases.