Abstract: Objective To investigate the effects of plasma homocysteine (Hcy), interleukin-6 (IL-6), and B-type natriuretic peptide (BNP) levels on the severity of coronary heart disease in elderly patients. Methods From January 2017 to December 2017, a total of 274 elderly patients with coronary heart disease were selected as the observation group, and 101 patients with normal coronary angiography were selected as the control group. According to the types of clinical diagnosis, patients were divided into stable angina pectoris group (75 cases), unstable angina pectoris group (110 cases) and acute myocardial infarction group (89 cases). The plasma levels of Hcy, IL-6 and BNP were tested, and their effects on the severity of coronary heart disease were analyzed. Results The levels of Hcy, IL-6 and BNP in the observation group were significantly higher than those in the control group (all P<0.01). The levels of Hcy, IL-6, and BNP in the stable angina pectoris group were significantly lower than those in the unstable angina pectoris group (all P<0.01), and those in the unstable angina pectoris group were significantly lower than those in the acute myocardial infarction group (all P<0.01). Conclusions The levels of Hcy, IL-6, and BNP in patients with coronary heart disease are significantly higher than those in normal people. The test of Hcy, IL-6, and BNP levels should be helpful to the clinical diagnosis of elderly coronary heart disease and its severity.