In recent years, thermoelectric materials have attracted widespread attention due to their ability to achieve direct conversion of electricity and heat. However, the low conversion efficiency of thermoelectric devices limits their practical applications. In order to improve their conversion efficiency, most research work focuses on improving the thermoelectric value of excellence (ZT) of thermoelectric materials. SnSe is currently a high-performance medium temperature thermoelectric material. In this paper, Ag doped polycrystalline Ag_xSn_1-xSe (x=0.0025, 0.005, 0.0075) thermoelectric materials were successfully prepared by hydrothermal method and under conditions lower than traditional sintering temperature. The results showed that the addition of Ag significantly improved the carrier concentration of the material, while maintaining a high Seebeck coefficient, resulting in a significant improvement in the electrical properties of the material. When x=0.0075, Ag_0.0075Sn_0.9925Se has a relatively high ZT value, reaching 1.2 at 800 K. However, after annealing treatment, the ZT value of the sample decreased to about 0.8 at 800 K.