Effects of different Y contents,including 0,0.93%,2.25% and 3.50%,on microstructure and mechanical properties of Mg-0.8Zn-0.35Zr alloy were investigated. The results reveal that grain size in the alloy can be refined with Y addition,furthermore,with increasing in Y content,the secondary phase on the grain boundary and lamellar structure in grain are increased. In addition,with Y content increase,the ambient and elevated tensile strength of the alloy are improved,and the ambient elongation exhibits the phenomena of first increase and then decrease,where it reaches 26% with 0.93% Y content,however,the elevated elongation is decreased,alternatively,elevated creep resistance of the alloy is obviously improved.