Abstract: Objective　To establish a clinical anatomic composite grading system and to evaluate the combined effects of the European Heart Surgery Risk Scoring System (EuroSCORE) Ⅱ and SYNTAX scoring system in predicting the prognosis of patients undergoing coronary artery bypass grafting (CABG). Methods　The perioperative data of CABG patients in Tianjin chest hospital from July 2017 to December 2018 were retrospectively analyzed. EuroSCOREⅡ and SYNTAX were used to stratify the cardiovascular risk of patients. According to the classification of the two systems, they were arranged and redistributed to construct the clinical anatomy composite grading system. The discrimination and calibration of the system were evaluated compared by EuroSCOREⅡ and SYNTAX. Results　The actual hospital mortality for 301 patients was 1.54% (20/1 301). According to the comparison of baseline data after grading by scoring system, there were significant differences between EuroSCORE Ⅱ groups except unstable angina pectoris and SYNTAX. There were significant differences in age, unstable angina pectoris and 30-day death between SYNTAX groups. There were significant differences in other variables except unstable angina pectoris, NYHA and peripheral arterial disease between composite grading system groups. The results of H-L goodness of fit test showed that EuroSCORE Ⅱ, SYNTAX and composite grading system had good fitting degree. ROC curve analysis showed that the accuracy of composite classification system was the best,(AUC=0.862). AUC of EuroSCORE Ⅱ and SYNTAX were 0.849 and 0.732 (P＜0.01). This indicates that the composite grading system can significantly improve the predictive ability of 30-day mortality after operation. Compared with EuroSCORE Ⅱ, NRI of composite grading system was 14.05% (Z=7.205, P＜0.01), compared with SYNTAX, NRI=37.85% (Z=4.240, P＜0.01). Conclusion　The composite classification system of EuroSCORE Ⅱ and SYNTAX can improve the ability of single type scoring system to predict the short-term mortality of CABG.