N-type Bi2Te2.7Se0.3 thermoelectric materials with Ga and K dual doping were synthesized by vacuum melting and hot pressing. XRD results indicate that Ga and K elements have been completely dissolved into the crystal structure of Bi2Te2.7Se0.3. The single-phase solid solution alloy has been formed. SEM results show that the bulk samples are compact with the laminated structure. Ga and K dual doping increases the Seebeck coefficient of Bi2Te2.7Se0.3 through Ga and K partial substitution of Bi in the most range of 300~500 K, while the electrical conductivity of the dual doped samples is improved. The thermal conductivity of the dual doped samples is higher than that of Bi2Te2.7Se0.3. The maximum ZT value reaches 1.05 at 500 K for Ga0.02Bi1.94K0.04Te3Se0.3 sample.