Abstract: Objective The infants with extremely low birth weight often require a longer period of intravenous nutrition to ensure their normal growth and development. The aim of this paper is to observe the effect of improved umbilical vein catheterization combined with PICC in the intravenous nutrition management of infants with extremely low birth weight. Methods A total of 48 infants with extremely low birth weight were divided into control group (28 cases) and observation group (20 cases) from March, 2015 to February, 2017. The infants of the control group received traditional umbilical vein catheter and PICC, while the infants of the observation group received the improved umbilical vein catheterization and PICC. The umbilical vein catheter indwelling time, incidence of umbilical bleeding, incidence of accidental catheter detachment, PICC indwelling time, rate of once puncture success, incidence of planned extubation, time to total gastrointestinal nutrition and hospital stay were observed. Results Umbilical vein catheter indwelling time of the observation group was significantly longer than that in the control group (P<0.05), the incidence of umbilical bleeding and accidental catheter detachment had no significant difference between the two groups (P>0.05); PICC indwelling time of the observation group was significantly longer than that in the control group (P<0.05), and incidence of once puncture success and planned extubation had no significant difference between the two groups (P>0.05); The time to total gastrointestinal nutrition and hospital stay of the observation group was significantly lower than those in the control group (P<0.05). Conclusion The improved umbilical vein catheterization combined with PICC can markedly prolong indwelling time, reduce the occurrence of adverse events, and shorten the time to whole gastrointestinal nutrition and hospital stay in infants with extremely low birth weight.