Objective To investigate the correlation between serum citrulline and neonatal necrotizing enterocolitis(NEC). Methods A total of 80 NEC children admitted to Panjin Liaoyou Baoshihau Hospital from April 2019 to March 2021 were selected as the study group.According to the modified BELL staging criteria, they were divided into group A(NEC stage Ⅰ, 26 cases), group B (NEC stage Ⅱ, 32 cases) and group C (NEC stage Ⅲ, 22 cases).Fifty healthy neonates who received physical examination at the same period were selected as the control group (CG).The serum levels of citrulline, procalcitonin (PCT) and C-reactive protein (CRP) were compared among all groups, and the correlation between serum citrulline level and PCT and CRP levels was analyzed.The receiver operating characteristic (ROC)curve of serum citrulline for neonatal NEC was drawn and the area under the curve(AUC)was calculated.Finally,80 children were divided into cured group (68 cases) and poor prognosis group (12 cases) according to clinical outcome, and the correlation between serum citrulline level and prognosis of NEC neonates was preliminarily analyzed. Results The serum levels of PCT and CRP in groups A, B and C were higher than those in CG group, and the levels of citrulline were lower than those in CG group, the differences were statistically significant (P＜0.05).The serum levels of PCT and CRP in group A were lower than those in groups B and C, and the levels of citrulline were higher than those in groups B and C, the differences were statistically significant (P＜0.05).The serum levels of PCT and CRP in group B were lower than those in group C, and the level of citrulline was higher than that in group C, the differences were statistically significant (P＜0.05).Serum citrulline level was negatively correlated with PCT and CRP levels in NEC children(r=-0.7209, -0.9511, P＜0.05).The serum citrulline level in the cured group was higher than that in the poor prognosis group, and the serum PCT and CRP levels were lower than those in the poor prognosis group, the differences were statistically significant (P＜0.05).Using 21.67 μmol/L as cut-off point, the diagnostic ROC curve of serum citline for NEC children was plotted, and the AUC was calculated to be 0.905 (95%CI=0.813-0.997, P＜0.001). Conclusion Serum citrulline levels are significantly different in children with NEC with different disease course and different prognosis, which can be considered for the diagnosis and prognosis analysis of NEC.