Objective To study the effect of extensively hydrolyzed formula on the growth and development in very low birth weight (VLBW) and extremely low birth weight (ELBW) infants.Methods A total of 375 VLBW or ELBW infants were enrolled and divided into an observation group (187 infants) and a control group (188 infants) using a random number table. The infants in the observation group were given extensively hydrolyzed formula, and when the amount of extensively hydrolyzed formula reached 10 mL/time, it was changed to the standard formula for preterm infants. The infants in the control group were given standard formula for preterm infants. Both groups were fed for 4 consecutive weeks and were compared in terms of incidence rate of feeding intolerance, time to establish full enteral feeding, time to complete meconium excretion, number of spontaneous bowel movements, growth and development, motilin level at 4 and 10 days after feeding, and incidence rate of infection.Results Compared with the control group, the observation group had a lower rate of feeding intolerance (P < 0.05), a shorter duration to full enteral feeding and time to complete meconium excretion (P < 0.05), a higher mean number of daily spontaneous bowel movements (P < 0.05), higher body weight (1 793±317 g vs 1 621±138 g; P < 0.05), head circumference (30.5±1.1 cm vs 30.0±1.6 cm; P < 0.05), and body length (43.9±1.2 cm vs 42.1±2.0 cm; P < 0.05), a higher motilin level at 4 and 10 days after feeding (P < 0.05), and a significantly lower infection rate (P < 0.05).Conclusions Extensively hydrolyzed formula can increase motilin level, improve gastrointestinal feeding tolerance, promote early growth and development, and reduce the incidence of infection in VLBW and ELBW infants.