Objective To evaluate the effect of delayed ligature of the umbilical cord on the blood volume in premature infants in early time. Methods From Oct 2007 to Jun 2010,194 premature infants with vaginal birth in department of genecology and obstetrics were randomly divided into routine ligature of the umbilical cord group (100 cases) and delayed ligature of the umbilical cord group (94 cases), comparision were made on ligature time, blood routine examination,blood pressure,oxyhemoglobin saturation and anemia incidence in 24 h,48 h,and 72 h after birth,and hemobilirubin on 1 d,2 d,3 d,and 7 d after birth. Results There were significant differences between the two groups in delayed ligature time [(100. 14 + 10. 57) s vs (22. 40 +5.02) s,P ＜0. 05)]. The hemoglobin and blood pressure in delayed ligature umbilical group were increased significantly(P ＜ 0. 05). There was 3 cases (3. 19%) of anemia in delayed ligature of the umbilical cord group, and 11 cases (11.00%) in routine ligature of the umbilical cord group, which showed significant difference (P ＜ 0. 05). And the hemobilirubin on 7 d after birth showed no significant difference between the two groups(P ＞ 0. 05). Conclusion Delayed ligature of umbilical cord has a significant influence on hemoglobin and blood pressure of premature infant. It can increase the blood volume, and reduce the incidence of anemia in early time.