Abstract: The characteristics of antiyeast substances produced by Lactobacillus,which were isolated from traditional dairy fermentation food in Inner Mongolia were studied. The results were showed as follows: The active substances of ALAC- 3 and ALAC- 4 were separated and purified by G- 100 Sephadex gel filtration chromatography.And then the G100-3 and G100-5 were obtained respectively.They were analytically pure and the molecular weights were about 80.49 ku and 40.32 ku respectively through SDS- PAGE. G100- 3 and G100- 5 were judged separately as the single substances according to the thin- layer chromatography.