Effect of the content of 1%Ag（mass fraction） on microstructure and property of microindentation of Sn9Zn solder was investigated by means of XRD、SEM and micro hardness tester etc. The results show that element Ag and Zn might form AgZn3 compound based on the calculation from theory of bond parameter function and experimental analysis. Due to Ag in the solder, the indentation displacement of Sn9Zn solder relative declines 11%, and its indentation hardness increases by 28%, reaching to 0.32 GPa. The reason that the property of microindentation of Sn9Zn solder is improved is existence and distribution of the intermetallic compound of Ag-Zn in the solder.