The first 1 000 days is a critical window of opportunity to promote healthy life， during which diet is an important factor. The study used randomized clinical trial to randomly divide the overweight or obese pregnant women into fermented dairy group intervened with fermented dairy from early pregnancy to six months postpartum and control group. Members in fermented dairy group were arranged 200 mL yogurt containing probiotics and prebiotics everyday. Fresh human milk samples， follow-up table for maternal-child health， and Edinburgh Postnatal Depression Scale(EPDS) were collected regularly postpartum to investigate the effect of fermented dairy on microbiota and macronutrients of human milk， mothers' body mass index (BMI) and postpartum depression， weight and neuropsychological development of infants. The results showed that compared with control group， fermented dairy intervention would significantly reduce the relative abundance of Veillonella， Cutibacterium， Streptococcus， Rothia， Neisseria and other microbiomes and improve the relative abundance of Ralstonia in human milk of 42 d postpartum. For human milk of 3-6 month postpartum， the relative abundance of Escherichia-Shigella， Subdoligranulum increased significantly and the relative of Streptococcus decreased significantly in the fermented dairy group compared with the control group. Besides， fermented dairy intervention improved significantly the content of true protein that contained functional proteins such as α-lactalbumin， lactoferrin and lysozyme in human milk of 3-6 months postpartum. There were no differences in other outcomes including mothers' body mass index， infants' weight and neuropsychological development. In conclusion， fermented dairy riched in probiotics and prebiotics could significantly regulate human milk's microbiota and true protein content， which might be helpful for infants' health.