Silver-tin oxide composite powders and silver powders were synthesized by hydrothermal method using NH3 to complex Ag+,SO2-3 to reduce Ag(NH3)+2 and Na2SnO3 as the source of tin. The powders were characterized by XRD, SEM and EDX. The results show that there are macroscopic and microscopic differences between two kinds of powders. Spherical silver powders are 3 μm in diameter, and silver-tin oxide composite powders are mainly flake of about 0.3 μm in thickness. Silver crystal in silver-tin oxide composite powders is preferentially oriented in the (111) crystallographic direction and its oriented index is 2.581. Crystal lattice parameter of silver crystal of silver tin-oxide composite powders is 0.409 34 nm, larger than 0.408 68 nm of silver powders. The XPS analysis shows that silver in silver-tin oxide composite powders is metallic silver and tin oxide in silver tin-oxide composite powders has the red shift for Sn4+(3d5/2) and O2-(1s).