Objective:To explore the incidence and risk factors of parastomal hernia after colostomy.Methods:The retrospective cohort study was conducted. The clinicopathological data of 145 patients undergoing colostomy in Xinxiang Central Hospital from January 2015 to January 2019 were collected. There were 86 males and 59 females, aged(59±11) years. Patients received pelvic and abdominal computed tomography once every 6 months after colostomy to detect the occurrence of parastomal hernia. Measurement data with normal distribution were represented as Mean± SD, and the independent sample t test was used for comparison between groups. Measurement data with skewed distribution were represented as M(range). Count data were represented as absolute numbers, and chi-square test or Fisher exact probability was used for comparison between groups. Kaplan-Meier method was used to analyze the cumulative annual incidence of parastomal hernia. Logarithmic rank test was used to analyze the cumulative incidence based on clinical variables. COX proportional hazard regression model was used for univariate and multivariate analyses. Results:(1) Incidence of parastomal hernia after colostomy. All the 145 patients were followed up for 86(range, 60?108)months after colostomy, of which 46 cases had parastomal hernia and 99 cases had no parastomal hernia. There were significant differences in gender, age, body mass index (BMI) and chronic liver disease between patients with and without parastomal hernia after colostomy ( χ2=23.28, t=13.27, χ2=6.17, 5.82, P<0.05). (2) Annual cumulative incidence of parastomal hernia after colostomy. The 1-, 3-, and 5-year cumulative incidence of parastromal hernia after colostomy was 8.5%, 26.4% and 42.7%, respectively. When the follow-up time is more than 5 years, the incidence of parastromal hernia tended to be stable. The 5-year incidence of parastomal hernia after colostomy in female patients was higher than that in male patients (70.7% vs 20.3%, χ2=12.37, P<0.05). The 5-year incidence of parastomal hernia after colostomy in patients≥60 years old was higher than that in patients under 60 years old (49.8% vs 20.0%, χ2=10.52, P<0.05). The 5-year incidence of parastomal hernia after colostomy in patients with BMI >28 kg/m 2 was higher than that in patients with BMI ≤28 kg/m 2 (55.3% vs 33.2%, χ2=11.76, P<0.05). The 5-year incidence of parastomal hernia after colostomy in patients with chronic liver disease was higher than that in patients with non-chronic liver disease (45.2% vs 32.4%, χ2=15.32, P<0.05). (3) Analysis of risk factors for parastomal hernia after colostomy. Results of multivariate analysis showed that female, age >60 years old, BMI ≥28 kg/m 2 and chronic liver disease were independent risk factors for parastomal hernia after colostomy ( hazard ratio=2.70, 2.51, 1.85, 5.88, 95% confidence intervals as 1.39?6.74, 1.01?4.59, 1.02?4.87, 1.05?8.24, P<0.05). Conclusions:The incidence of parastomal hernia after colostomy is increasing year by year, and tends to be stable after 5 years. Female, age >60 years old, BMI≥28 kg/m 2, and chronic liver disease are independent risk factors for parastomal hernia after colostomy.