SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports.But the polycrystalline SnSe possesses much lower performance especially for the low carrier mobility and electrical con-ductivity.We firstly attempted to explain and verify the difference in the electrical conductivity as a function of temperature between p-type crystalline and polycrystalline SnSe by considering the grain boundary effects in the polycrystalline samples.On the basis of 2％Na doping to optimize the carrier concentration,the carrier mobility is improved by further introducing In,leading to enhanced carrier mobility from 3 to 9 cm2·V-1·s-1 in polycrystalline SnSe.Moreover,In doping introduces extra resonant levels in SnSe,which increases the density of states near Fermi level and leads to an enhanced band effective mass.Large Seebeck coefficient of～205 μV·K-1 at 300 K and maximum power factor of～7.5 μW·cm-1·K-2 at 773 K can be obtained in the Sn0.975Na0.02In0.005Se sample,leading to a competitively high dimensionless figure of merit(ZT)value exceeding 1.1 at 773 K.