Abstract: The firstprinciples calculations of electronic property for doped PbS are investigated based on the density functional theory and generalized gradient approximation. Firstly, among the three substitutional impurities (Cd, Sn, Sb) with constant dopant concentration, the most stable structure is obtained through the analysis of the formation energy for different doping position. Then, the band structures of three doped systems are calculated. It is found that the band gaps decrease monotonically with the impuritys atomic number after doping, in addition to the shifted band structures. Finally, the optical properties of three doped systems are obtained, mainly including the impurity peak and the redshifted peak in the dielectric functions, and the expansion of absorption band ranges for doped systems. The lowest reflectivity peak arises in Cddoped PbS.