Abstract: OBJECTIVE The risk factors of urinary tract infection after hydronephrosis in children were analyzed. METHODS A total of 79 cases of children admitted to our hospital from Jan. 2016 to Jul. 2020 who underwent hydronephrosis were recruited. Twenty-three cases of children with postoperative urinary tract infection were divided into the infection group, and 56 cases of children without postoperative urinary tract infection were divided into the non-infection group. To observe the distribution of pathogenic bacteria in children complicated with urinary tract infection after hydronephrosis, and to conduct univariate and multivariate Logistic regression analysis of the clinical data in children undergoing hydronephrosis, to explore the related risk factors of postoperative urinary tract infection in children, and to propose corresponding preventive measures. RESULTS The results showed that specimens from 3 children for postoperative urine bacterial culture were positive, including 1 case of Klebsiella pneumoniae, 1 case of Serratia marcescens and 1 case of Enterobacter aerogenes. Univariate analysis showed that urinary tract infection after hydronephrosis and age, degree of hydronephrosis, operation duration, hospitalization days, nutritional status, and phimosis were the independent risk factors of urinary tract infection after hydronephrosis in children; the differences between them were significant（all P＜0.05）. Multivariate logistic regression analysis showed that postoperative double J tube placement, postoperative reflux, and phimosis were risk factors of urinary tract infection after surgery for children with hydronephrosis, and the difference was significant（P＜0.05）. CONCLUSION The main risk factors of urinary tract infection in children with hydronephrosis after operation are double J tube placement, postoperative reflux and phimosis. Nurses should draw up corresponding nursing plans according to individual differences of patients.