Objective To investigate the effect of individualized breast milk fortifier in breastfed premature infants, in order to provide reference for the appropriate feeding of premature infants. Methods A total of 120 premature infants were selected from January 2016 to December 2017 in Tanggu Obstetrics and Gynecology Hospital of Binhai District, Tianjin, who were hospitalized in pediatrics department and monitored their growth and development in Tianjin Binhai New Area Women and Children Health and Family Planning Service Center regularly. The participants were randomly divided into two groups, with 60 cases in each group. The control group was fed with standard breast milk fortifier, while the observation group was fed with individualized breast milk fortifier according to the protein intake of premature infants. The weight, length and head circumference, and feeding complications of the two groups were compared. Results The body weight, body length and head circumference of premature infants in two groups were higher in 1 month, 2 months and 3 months after feeding, with significant time influence(P<0.05). And these indicators in the observation group were higher than those in the control group, with significant intervention influence(P<0.05). The incidence rates of feeding intolerance and necrotizing enterocolitis in the observation group were significantly lower than those in the control group (χ²=4.821、5.217,P<0.05). Conclusions Compared with the standard breast-feeding agent, individualized breast milk fortifying agent can promote the physical growth of premature infants better. And the individualized breast milk fortifying is safer than standard breastfeeding fortifier, because it can reduce the incidence of feeding complications.