Objective To explore the application of MRI in the differential diagnosis of high-and low-risk thymoma.Methods The data of patients with pathologically confirmed thymoma were collected bidirectionally,and the differences in clinical data,MRI image characteristics of lesions,signal characteristics and apparent diffusion coefficient(ADC)values were compared and analyzed between high-and low-risk thymoma according to the pathological subtype.The receiver operating characteristic(ROC)curve analysis was used to screen out meaningful features,then the diagnostic efficacy and combined prediction probability of indicators were evaluated.Results There was no significant difference in clinical data(P＞0.001).The morphology of high-risk lesions was mainly irregular,while that of low-risk lesions was mainly regular.The edges of high-risk lesions were mostly not smooth,and the edges of low-risk lesions were mostly smooth.The enhancement degree of high-risk lesions was higher than that of low-risk lesions,and the ADC value was lower than that of low-risk lesions,with statistical significance(P＜0.001),in which the ADC value area under the curve(AUC)was higher than other indicators(AUC=0.968),and the combined prediction probability of indicators was the highest(AUC=0.981).Conclusion MRI shows great potential application value in preoperative differential diagnosis of high-and low-risk thymoma.