Oxygen tolerated bifid bacteria are selected in this paper to mix with different yogurt culture with comparison made on the effect of different inoculating proportions on the quantity of bifid bacteria in the fermented milk during the storage time. Results show that the number of active bifid bacteria is high in the fermented milk although the inoculating proportion is low (2%).The number of active bifid bacteria rises up to 10 8 cfu/mL within 10 days, and on the 15th day the number soars up to 10 7~...