Objective: To analyze the predictive value of umbilical arterial cord pH on complications of hospitalized neonates after cesarean section. Methods: This was a retrospective cohort study and carried out in Peking University First Hospital from January 1,2017 to June 30,2017. Neonates who were deli-vered by cesarean section were enrolled. The primary endpoint was the incidence of complications during in-hospital stay (including infection,aspiration pneumonia,myocardial damage,etc.). The subjects were divided into two groups:with or without complication. The umbilical arterial cord pH values were compared between the two groups. Perinatal baseline characteristics of maternal and neonatal data were recorded. The ROC curve was used to analyze the value of umbilical arterial cord pH in predicting neonatal complications during hospitalization. Multivariate Logistic regression was employed to analyze the potential risk factors of neonatal complications. Results: In the study,872 neonates were included in the final analysis (541 in elective surgery and 331 in emergency surgery). The overall incidence of neonatal complications during hospitalization was 14.1%. The first three higher incidences were infection,aspiration pneumonia and myocardial damage. The average pH value in neonates without complication was 7.31 while 7.29 in neonates with complication. There was statistical significance between the two groups (P<0.001). The overall incidence of pH≤7.20 was 3.1% (27/872). The patients in neonates without complication had higher incidence of pH≤7.20 than those in neonates with complication (1.6% vs. 12.2%, P<0.001). Multivariate Logistic regression showed 6 risk factors of neonatal hospitalized complications including preterm delivery (OR=8.224,95%CI:4.910-13.777, P<0.001),pregnancy-induced hypertension (OR=1.886,95%CI:1.004-3.546,P=0.049), intrauterine growth restriction (OR=4.429,95%CI:1.280-15.330,P=0.019), emergency cesarean section (OR=2.711,95%CI:1.682-4.369,P<0.001),umbilical arterial blood gas pH≤7.20 (OR=7.420,95%CI:2.951-18.655,P<0.001) and 5-minute Apgar score <10 scores (OR=11.849,95%CI:3.977-35.128,P<0.001). The areas under the ROC curve of umbilical arterial blood gas pH in all neonatal,elective and emergency cesarean section were 0.570 (95%CI:0.508-0.633,P=0.012),0.559 (95%CI:0.465-0.652,P=0.189) and 0.617 (95%CI:0.538-0.697,P=0.002),respectively. Conclusion: Umbilical arterial cord pH≤7.20 was related with increased incidence of neonatal complications after cesarean section,but ROC curve analysis showed a lower predictive value.