Gaseous penetration technique was adopted to improve the electrical conductivity of BaTiO3 powders and the effects of penetration temperature on the structure and electrical conductivity of Sm-modified BaTiO3 powders were studied. It was observed that the penetration of Sm made the resistivity of BaTiO3 powders decrease with the increase in the penetration temperature and decreased to the lowest point of established preliminarily to get the mathematical expression by the fitting method. Through X-ray diffraction (XRD) analysis, the new phases of Sm2O3 and Ba4Ti2O27 were detected. It was indicated that intricate reactions related to Sm took place during the penetration process and led to the Ti-rich state of the system. The Fourier transform infrared (FTIR) spectrum illustrated that the bonds of Ti-O octahedron was strengthened by substitution of Sm3+ at Ti4+ sites, which led to the growth of Ti:Ba ratio. The analysis results of scanning electron microscopy (SEM)indicated that the particle size of Sm-modified BaTiO3 powders progressed with the penetration temperature increasing.