Yeast cells’ activity and tolerance to freeze-thaw stress has an important influence on fermented products and frozen-dough technology. Soy peptides, casein peptone, and yeast nitrogen base were used as different yeast medium nitrogen sources to culture yeast cells. The effects of soy peptide on yeast cells’ activity and the tolerance to freeze-thaw stress were evaluated based on the growth curves, survival rates after freezing, cell wet weights, and dough fermentation. The results showed that the more soy peptides were added, the more yeast biomass was obtained, which did not increase when soy peptides reached 25g/L or higher. Therefore, the optimum amount of soy peptides was 25g/L. Yeast cells had a higher survival rate when they were incubated in media containing soy peptides, and the corresponding dough also retained better fermenting capability after freeze-thaw steps. Compared with other nitrogen sources, soy peptides increased the cell biomass and improved the cell tolerance to freeze-thaw stress and the fermentation effect.