Objective:To investigate the correlation between the dynamic changes of the superior mesenteric artery (SMA) blood flow after umbilical cord milking (UCM)detected and feeding tolerance in premature infants.Methods:This was a prospective study a total of 88 premature infants delivered in Shanghai Jiading Maternal and Child Health Care Hospital from June 2018 to February 2020 were randomly divided into UCM group(45 cases) and early cord clamping group (ECC group, 43 cases). SMA blood flow indexes 15 min before the first feeding (prefeed) and 60 min after the first feeding (post-feed) were detected using the GE Voluson 730 Ultrasound Machine, including the peak systolic velocity (PSV), time-averaged mean velocity (TAMV), pulsatility index (PI) and resistance index (RI). The gestational age, birth weight, the weight at discharge, SMA blood flow indexes, time to achieve enteral nutrition, length of stay and incidence of complications between the two groups were analyzed using t test, Chi- square test or Fisher′ s exact test. Results:(1)There were no significant differences in the gestational age, birth weight, the mother′s hemoglobin before deliver, and the incidence of complications between UCM group and ECC group (all P>0.05). (2) Except for RI, all SMA blood flow indexes were higher in UCM group than those of ECC group.However, only prefeed TAMV[(24.74±11.47) cm/s vs.(20.24±7.71) cm/s], post-feed TAMV[(42.11±15.74 )cm/s vs.(28.31±9.99) cm/s] and TAMV change before and after feeding [(13.89-20.86) cm/s vs.(5.31-10.82) cm/s]were detected to be significantly higher in UCM group than those of ECC group (all P<0.05). (3) Multivariable linear regression analysis showed that the gestational age, birth weight, PSV elevation and PI reduction were negatively correlated with the length of adequate feeding (all P<0.05). (4) The time to achieve enteral nutrition[(11.75±7.36) d vs.(13.38±8.12) d] and the incidence of feeding intolerance [13.3% (6/45 cases) vs.20.9%(9/43 cases)] were lower in UCM group than those of ECC group, although no significant differences were detected (all P>0.05). Conclusions:UCM increases the hemoglobin level in premature infants, which is beneficial to feeding tolerance of premature infants by improving SMA blood flow.