Abstract： Objective:To explore the risk factors for nonsurgical reduction failure and to construct a clinical prediction model in children with intussusception.Methods:From June 2021 to June 2022, retrospective analysis was performed for 281 hospitalized children with intussusception aged 2 years and below undergoing nonsurgical reduction. There were 195 boys and 86 girls with a mean age of (16.46±10.97) months. Based upon the results of enema reduction, they were assigned into two groups of success (n=234) and failure (n=47). Demographic profiles, clinical manifestations, laboratory tests, ultrasonic signs and enema reduction modes were recorded. The clinical data of two groups were statistically analyzed with one-way analysis of independent sample t, chi-square and Mann-Whitney U tests. Parameters with statistically significant inter-group differences were included as variables for multivariate logistic regression analysis to screen out the risk factors of nonsurgical reduction failure. And a nomogram was constructed for establishing a prediction model. The validation dataset was utilized for validating the model. Receiver operating characteristic (ROC) curve for predicting nonsurgical reduction failure by the prediction model was plotted and area under the ROC curve (AUC) calculated. Results:Univariate analysis indicated that proportion of age, duration of symptoms, vomiting, hematochezia, abdominal distension, fever, location of mass, peritoneal fluid, abnormal blood flow signal on ultrasonic scans, proportion of enema reduction, level of C-reactive protein (CRP) and length of intestinal invagination were all higher in failure group than those in success group while the levels of hemoglobin (Hb) and sodium (Na) were lower than those in success group (all P<0.05). Binary logistic regression analysis showed that age under 1 year ( OR=27.70, 95% CI: 6.06-126.62), vomiting ( OR=0.05, 95% CI: 0.01-0.28), abdominal distension ( OR=0.11, 95% CI: 0.02-0.70), lower Hb ( OR=1.06, 95% CI: 1.01-1.10), left-sided mass ( OR=0.04, 95% CI: 0.01-0.20) and longer intestinal invagination ( OR=0.49, 95% CI: 0.32-0.76) were risk factors for nonsurgical reduction failure (all P<0.05). AUC of ROC curve of the prediction model for nonsurgical reduction failure was 0.975 (95% CI: 0.957-0.995, P<0.001) with a sensitivity of 94.9% and a specificity of 87.2%. AUC of ROC curve predicting nonsurgical reduction failure in tvalidated concentrated prediction model was 0.966 (95% CI: 0.937-0.995, P<0.001) with a sensitivity of 90.0% and a specificity of 95.7%. Conclusion:Age <1 year, vomiting, abdominal distension, lower Hb, left-sided mass and longer intestinal invagination are risk factors for failed nonsurgical reduction of intussusception in children aged 2 years and below. And the established nomogram model has demonstrated decent predictive capability.