Due to the increasing interest in the thermoelectric properties of materials and finding new materials that have thermoelectric applications, In this work, the structural and thermoelectric properties of Ag2SiS3 compounds with monoclinic crystal structures have been investigated using density functional theory in the LDA approximation with the quasi-potential method. In the investigation of the band structure, the value of the band gap was obtained in the approximation of LDA=1.21 eV, LDA+U=1.42 eV and HSE=2.26 eV electron volts, which is in good agreement with the work of others and has an indirect band gap between the Γ and E dots. The thermoelectric properties of the Ag2SiS3 compound were also investigated, and the value of the figure of merit ZT=1 was obtained from the measured results. It was found that the application of Hubbard and the HSE hybrid function did not have a significant effect on the value of the figure of merit, but it affected other compound properties such as thermal conductivity and electrical conductivity. The Ag2SiS3 compound is a suitable compound for thermoelectric applications.