The p-type SnxBi0.5-xSb1.5Te3 thermoelectric materials with high ZT values have been prepared by vacuum melting, ball milling, cold-pressing and ambient pressure sintering. The effect of Sn content on the crystal structure, microscopic appearance, thermoelectric properties for SnxBi0.5-xSb1.5Te3 materials was investigated. As a result, the crystal structure of SnxBi0.5-xSb1.5Te3 thermoelectric materials is the rhombohedral structure; Bi0.5Sb1.5Te3 based thermoelectric materials contain more nanostructure defects with adding alloying element Sn. The addition of the alloying element Sn can increase carrier concentration and DOS effective mass to improve the electrical conductivity and power factor (PF). While, the reduction in lattice thermal conductivity is attributed to the enhanced phonon scattering. Eventually, the power factor reaches 3.10 mW·m-1·K-2, the lattice thermal conductivity is 0.358 W·m-1·K-1 and the ZT value is 1.25 at 300 K for Sn0.015Bi0.485Sb1.5Te3. And，in the temperature range of 300～400K，the ZT values for the Sn0.015Bi0.485Sb1.5Te3 are 1.25～1.33.