Objective To compare the effects of two different types of enteral nutrition on postpyloric feeding critical ill patients.Methods A prospective study was conducted to continuously collect 60 critical ill patients with indications ofpost-pyloric feeding in ICU and NICU wards of our hospital from January 2016 to December 2018.They were randomly (random number) divided into the peptide-based enteral nutrition (PBEN) group and intact protein enteral nutrition (IPEN) group with 30 patients in each group.Enteral nutrition was started immediately within 24 h after the nasointestinal tube was placed,and the PBEN group was treated with peptide-based enteral nutrition,while the IPEN group was treated with intact protein enteral nutrition.The nutritional metabolism index,intestinal barrier index on the 7th and 14th days after enteral nutrition treatment were observed and compared.The enteral feeding complications,incidence of feeding intolerance,gastrointestinal adaptability and 7-day enteral nutrition compliance rate of the two groups during the enteral nutrition were also observed and compared.Chi-square test was used for counting data and t test was used for measuring data.Results On the 7th and 14th days after enteral nutrition therapy,there was no statistical difference in nutritional metabolism indexes between the two groups (P＞0.05).In comparison of intestinal barrier indexes,diamine oxidase (DAO) level in the PBEN group was lower than that in the IPEN group at the same time,and the difference was statistically significant [7th day:(6.1±2.9) U/mL vs (7.8±2.7) U/mL,t=-2.354,P=0.019;14th day:(4.7±1.6) U/mL vs (6.9±2.0) U/mL,t=-3.285,P=0.004].During enteral nutrition,the diarrhea rate of patients in the PBEN group was slightly higher than that in the IPEN group (6.6％ vs 3.3％),while the abdominal distension rate in the IPEN group was slightly higher (3.3％ vs 10.0％),but there was no statistical difference between the two groups (P＞0.05).The gastrointestinal adaptation time of patients in the PBEN group was significantly shorter than that in the IPEN group [(7.8±1.3) h vs (9.1±2.0) h,t=-2.334,P=0.027].The 7-day enteral nutrition compliance rate showed no significant difference between the two groups(P＞0.05).Conclusions Diarrhea was the main complication in the PBEN group and abdominal distension was the main complication in the IPEN group for post-pyloric feeding critical ill patients.Peptide-based enteral nutrition could repair the intestinal barrier function of post-pyloric feeding critical ill patients and increase the adaptability of gastrointestinal tract in the initial stage of enteral nutrition.