Objective：This study aims to investigate the risk factors of urethral fistula after Onlay-island flap urethroplasty for middle hypospadias. Methods：We conducted a retrospective and contrastive analysis which contained patients（n=207）receiving Onlay-island flap urethroplasty for hypospadias from March 2017 to June 2019，in the urology department of Nanjing Children’s Hospital Affiliattd of Nanjing Medical University. The data collected included the age，weight，surgeon，operation time，position of urethral opening，length of urethral defect，straightening method and anesthesia method（general anesthesia，general anesthesia combined with Caudal anesthesia）. The possible risk factors of complications were analyzed by single and multiple factors. Results：A total of 267 cases of children conform to the study. The median age was 19 months（5~132 months）. The mean operation time was 87.19 min and weight was 13.33 kg. By univariate analysis，we found that the operative age（P=0.123），weight（P=0.155）and defect distance（P=0.096）were not related to the occurrence of urethral fistula after hypospadias. Similarly，the incidence of urethral fistula in children receiving sacral anesthesia was not significantly different from receiving general anesthesia alone（29.7% vs. 25.8%，P=0.953）. While the operative time（P=0.010），surgeon （P=0.001）and straighting method（P=0.003） affect it.However，Based on the univariate results，we conducted further multivariate analysis and found that experience of surgeons（P=0.031）plays a key role in urinary fistula. Conclusion：The occurrence of urethral fistula after operation of hypospadias has nothing to do with anesthesia technique，age at operation，weight，straightening method and operation time. but has related to surgeon.