Objective To modify the insertion length of orogastric tube placement in premature infants and to evaluate its effect. Methods A total of 306 premature infants undergoing orogastric tube insertion in the Neonatal Center of a tertiary A hospital in Beijing were selected as the study subjects. 155 premature infants undergoing orogastric tube insertion from August 2019 to April 2021 were selected as the test group,and 151 premature infants from March 2018 to July 2019 were in the control group. The effects of different predicting methods on the correct placement rate of the orogastric tube tip,drainage volume before gastrointestinal decompression,number of vomiting episodes,and the total time of gastrointestinal decompression were compared in 2 groups. Results The correct placement rate of orogastric tube tip was 85.81% in the test group and 15.23% in the control group,and the difference was statistically significant（P<0.001）. The drainage volume 3 days before gastrointestinal decompression in the test group was higher than that in the control group,and the difference was statistically significant（t=14.38,t=15.78,t=11.06,all,P<0.001）. The incidence rate of vomiting during gastrointestinal decompression in the test group was lower than that in the control group（χ²=7.05）,and the difference was statistically significant（P=0.008）. The total time of gastrointestinal decompression was shorter than that in the control group（t=12.74）,and the difference was statistically significant（P<0.001）. Conclusion The modified method of predicting insertion length of orogastric tube in premature infants can improve the accuracy of optimal placement for the orogastric tube tip,avoid misplacement of the orogastric tube,and improve the effect of gastrointestinal decompression.