Abstract: Creep curves were obtained by indentation creep test for Sn-4.8Bi and Sn-4.8Bi-3.4Ag alloy, and the changing rule of indentation creep with load and temperature was summarized.The chemical compositions of precipitated phases and the micro-structures before creep and after creep were analyzed by X-ray diffractometry(XRD) and scanning electron microscope(SEM).The results show that the creep resistance of Sn-Bi solder is improved by adding Ag.The precipitated phase of Sn-Bi alloy is Biby contrasting the precipitated phases Ag3Sn and decreased Bi in Sn-Bi-Ag alloy before creep.The granular phase Bi is fine and forms diffuse distribution in the matrix during creep deformation in Sn-Bi solder.The stripy phase Ag3Sn is fine, the massive phase is coarse, but phase Bi further decreases in Sn-Bi-Ag solder after creep.The stripy phase and massive phase Ag3Sn containing Ag element and fined Bi play an important role for the improvement of the creep resistance of Sn-Bi-Ag alloys.