Abstract： Objective:To examine the prognosis factors of postoperative cardiac complications in colorectal cancer patients co-morbidated with coronary artery disease.Methods:Clinical data of 449 patients colorectal cancer patients co-morbidated with coronary artery disease accepted redical surgery from April 2013 to April 2020 at Department of General Surgery, Peking Union Medical College Hospital were analyzed retrospectively. There were 306 males and 143 females, aging (68.7±8.9) years (range: 44 to 89 years). Postoperative acute coronary syndrome, new-onset arrhythmia and heart failure that causes clinical symptoms were recorded as cardiac complications. t test, χ 2 test and Fisher exact test were used for univariate analysis of prognosis factors of postoperative cardiac events. The variables with P<0.05 were included in the multivariate Logistic regression was used to determine the independent prognosis factors. Results:After surgery, 44 patients (9.8%) suffered from at least one cardiac event, including 30 patients with acute coronary syndrome, 19 patients with new-onset arrhythmia and 9 patients with heart failure. There were 3 deaths in the cohort within 30 days after surgery. Two patients died from cardiac-related complications, and one from septic shock due to postoperative anastomotic leaks. On Univariate analysis showed that cardiac complications were associated with age ≥80 years, co-morbidated diabetes, emergency surgery, re-operation, anastomotic leakage, intestinal flora disorder and elevation of preoperative neutrophil-lymphocyte ratio (χ 2: 4.308 to 12.219, all P<0.05). Multivariate Logistic regression analysis identified age ≥80 years ( OR=3.195, 95% CI: 1.379 to 7.407, P=0.007), co-morbidated diabetes ( OR=2.551, 95% CI: 1.294 to 5.025, P=0.007), emergency surgery ( OR=4.717, 95% CI: 1.052 to 20.833, P=0.043), and elevated preoperative neutrophil-lymphocyte ratio ( OR=1.114, 95% CI: 1.018 to 1.218, P=0.018) as independent prognosis factors for cardiac complications. Conclusions:Emergency surgery, advanced age, co-morbidated type 2 diabetes and elevated preoperative neutrophil-lymphocyte ratio may increase the risk of postoperative cardiac complications in colorectal cancer patients with coronary artery disease. Surgeons should strictly master surgical indications, pay attention to preoperative assessment, perioperative monitoring, and diagnosis and treatment of postoperative complications in order to reduce the risk of complications.