Objective To retrospectively analyze the changes of pH, alkali surplus (BE) in arterial blood gas, platelet/lymphocyte (PLR) and neutrophil/lymphocyte ratio (NLR) in serum of 139 cases of neonatal necrotizing enterocolitis (NEC), and to explore their early diagnostic value for NEC. Methods A total of 139 newborns admitted to our Hospital from January 2020 to January 2023 were selected as the study subjects. They were divided into a NEC group of 89 cases (NEC patients) and a control group of 50 cases (non NEC patients) based on whether they were diagnosed with NEC after discharge. The NEC group was divided into stageⅠ of 14 cases according to the modified Bell NEC diagnostic criteria; 64 cases in Phase Ⅱ; 11 cases in stage Ⅲ. The differences of arterial blood pH, BE, platelet/lymphocyte (PLR) and neutrophil/lymphocyte ratio (NLR) in serum between the two groups were analyzed. Multiple logistic regression analysis was used to identify the risk factors affecting NEC. Results Showed that there was a statistically significant difference (P＜0.05) between the two groups in terms of body mass at onset and incidence of asphyxia during childbirth. The remaining alkaline levels in the NEC group were significantly lower than those in the control group, and the levels of platelet/lymphocyte (PLR) and neutrophil/lymphocyte ratio (NLR) in the serum of the NEC group were significantly higher than those in the control group, with statistical significance (P＜0.05). The pH of stage Ⅲ patients was significantly lower than that of stage Ⅱ patients, the residual level of alkali in stage Ⅲ patients was lower than that of stage Ⅰ and Ⅱ patients, and the PLR level in stage III patients was higher than that of stage Ⅰ and Ⅱ patients, with a statistically significant difference (P＜0.05). The ROC curve analysis results showed that the area under the curve (AUC) for the combined detection of alkali residue, PLR, and NLR in the diagnosis of NEC was 0.694, with a sensitivity of 57.3% and a specificity of 80%, which was greater than the AUC detected separately for the three indicators. The results of multivariate logistic regression analysis showed that premature infants and residual alkali were independent risk factors for developing NEC in children (P＜0.05).Conclusion The combined detection of alkali residue, PLR, and NLR has better diagnostic value for children with NEC than individual detection, and the pH of stage Ⅲ NEC patients significantly decreases