Objective To compare the predictive effectiveness of the COMHON scale and the Braden scale in the risk assessment of pressure injury for ICU patients after mediastinal surgery. Methods A total of 232 ICU patients after mediastinal surgery from thoracic surgery department were selected conveniently, then they were conducted risk assessment of pressure injury using the COMHON scale and the Braden scale. Results During the 72 hours observation period, 29 patients (12.5%) suffered from pressure injury, and all of them were in stage I. When the patients were assessed using the two scales, there were significant differences in the total scores between the pressure injury group and the non-pressure injury group (P＜0.01 for both). The area under the ROC curve of the Braden scale was 0.747, and when the total score was 13.5, the Youden index was 0.522, which achieved the best predicted value; and the area under the ROC curve of the COMHON scale was 0.976, when the total score was 9.5, the Yoden Index was 0.828, which had the maximal predicted value. Conclusion Both the Braden scale and the COMHON scale can effectively assess the risk of pressure injury for ICU patients after mediastinal surgery, and the predictive performance of the COMHON scale is better than that of the Braden scale.