Recently, Cu₂SnSe₃-based compounds, as a new environment-friendly thermoelectric material, have attracted worldwide attentions. However, the pristine Cu₂SnSe₃ compound possesses relatively low carrier concentration and thus an inferior electronic transport properties. To optimize the thermoelectric properties of Cu₂SnSe₃- based compounds, herein, two series of Cu₂SnSe_3-xTe_x (x=0-0.2) and Cu₂Sn_1-yIn_ySe_2.9Te_0.1 (y=0.005-0.03) samples were synthesized through traditional melting-annealing technique combined with plasma activated sintering (PAS). The role of Te and In co-doping on the thermoelectric properties of Cu₂SnSe₃-based compounds were systematically investigated. The solubility limit of Te in the Cu₂SnSe_3-xTe_x compounds is around 0.10. The substitution of Te on Se site significantly increases the effective mass of charge carrier from 0.2m_e for pristine Cu₂SnSe₃ compound to 0.45m_e for Cu₂SnSe_2.9Te_0.1 compound, which improves the power factor of the material. Cu₂SnSe_2.99Te_0.01 compound attains the maximum power factor of 1.37 μW·cm^-1·K^-2 at 300 K. To further improve the electronic transport properties of the material, Cu₂SnSe_2.9Te_0.1 was chosen as the matrix and In was selected to dope on Sn site. We found that doping with In significantly improves the carrier concentration of Cu₂SnSe₃-based compounds from 5.96×10¹⁸ cm^-3 for Cu₂SnSe_2.9Te_0.1 to 2.06×10²⁰ cm^-3 for Cu₂Sn_0.975In_0.025Se_2.9Te_0.1, which promotes the participation of multiple valence bands in the electronic transport. All these produce the great enhancements on the electrical conductivity, effective mass of charge carriers and power factor. As a result, Cu₂Sn_0.995In_0.005Se_2.9Te_0.1 compound obtains the maximum power factor of 5.69 μW·cm^-1·K^-2 at 473 K. Due to the significant improvement of electrical transport performance and the decrease in lattice thermal conductivity, the maximum ZT of 0.4 is achieved for Cu₂Sn_0.985In_0.025Se_2.9Te_0.1 compound at 773 K, which is 4 times higher than that of pristine Cu₂SnSe₃ compound.