Abstract:Constipation is a common digestive tract disease.Probiotics can relieve constipation by maintaining the balance of intestinal flora，producing beneficial metabolites，promoting intestinal peristalsis，and alleviating intestinal inflammation.The dynamic in vitro bionic digestive system was employed to study the digestion of the milk fermented with Bifidobacterium lactis Probio-M8.The effect of the fermented milk on constipation in a human population was studied.The results showed that B.lactis Probio-M8 could well tolerate the gastrointestinal fluid and enter the host body in the form of live bacteria to exert probiotic effects.The participants showed improved defecation frequency，stool form，and bowel movement effort after drinking the milk fermented with B.lactis Probio-M8.Moreover，the improvement of the stool scale and the bowel movement effort was particularly obvious in the people aged 40-50 years.