Abstract: Objective To explore the application of plasma receptor interaction protein 3 in the diagnosis and prognosis of neonates with necrotizing enterocolitis (NEC). Methods A total of 57 NEC neonates who were admitted to the Affiliated Suzhou Hospital of Nanjing Medical University from September 2019 to February 2021 were selected as a NEC group. Meanwhile, 57 neonates with non-infectious diseases were selected as a control group. Their plasma RIP3 levels were detected by enzyme-linked immunosorbent assay, and the value of plasma RIP3 in the diagnosis and prognostic assessment of NEC was analyzed. Results The plasma RIP3 level of neonates in NEC Ⅱ stage (26.64±1.07 μg/L) was significantly higher than those in NEC stage Ⅱ (18.91±1.32 μg/L) and the control group (12.71±0.75 μg/L) (P=0.002). The area under ROC curve of RIP3 for the diagnosis of NEC was 0.918. The sensitivity, specificity and Youden index of RIP3 were 94.7%, 62.5%, and 0.57 at the cut-off value of 19.50 μg/L. The RIP3 of dead neonates (29.35 μg/L) were significantly higher than those in the survival group (21.65 μg/L) (P<0.05). According to Kaplan-Meier survival method, the time to full enteral nutrition of NEC was statistically different in the low expression group (RIP3<28 μg/L) and the high expression group (RIP3≥28 μg/L). Conclusions Plasma RIP3 levels are closely related to the clinical stage and prognosis of neonates with NEC, and have potential clinical application value for the diagnosis of NEC.