The phase diagram of Zn-Al binary system was investigated by means of differential scanning calorimeter （DSC）, X-ray diffraction （XRD） and pushrod dilatometer （PRD）. Advents of β（ZnAl） phase on XRD curves indicates that there exists β（ZnAl） solid solution single phase zone in the Zn-Al alloy system. DSC analysis shows that eutectoid reaction occurs in the range of 274²79 ℃, and PRD analysis reveals that non-transformation is discovered at 340 ℃. Partial Zn-Al binary system phase diagram were sketched based on above results, which provides a reference for application of practical phase transformation in high Al-Zn alloy.