The microstructure, micro-hardness and tensile behavior of bulk Sn-3.5Ag alloy were studied as a function of cooling rate. Sn-3.5Ag alloy samples with the controlled cooling rates of 101, 103 and 106 K/S of were obtained by cooling specimens in different media: air, water and rush cold. The microscopic analysis and mechanical properties test were conducted. Results show that the cooling rat has a significant effect on the secondary dendrite size and distribution of β-Sn phase. The β-Sn grain average size and the secondary dendrite arm space are gradually reduced with the increase of cooling rate, Ag3Sn grain also become smaller, and distribute more uniformly. Besides, the micro-hardness and tensile properties with increasing cooling rate improve. Finally, it is concluded that the microstructure and the distribution of Ag3Sn grains influence obviously the mechanical properties, and Ag3Sn grains play a dispersion strengthened role in the alloy