Aim To compare the difference of serum α-Klotho protein concentration in patients between acute myocardial infarction and chronic stable angina pectoris. Methods Patients who suffered coronary heart disease and treated by coronary angiography were selected as the research object. Within 24 hours after the patients were hospitalized, their medical history, physiological and chemical data and serum α-Klotho protein concentration were collected. Univariate analysis method and multivariate analysis method were used to analyze the difference of serum α-Klotho protein concentration in acute myocardial infarction group （n＝84） and chronic stable angina pectoris group （n＝90）. Results The serum α-Klotho protein concentration in acute myocardial infarction group was lower than that in chronic stable angina pectoris group （903.19±558.13 ng/L vs 1075.10±535.29 ng/L）, and the difference was statistically significant （P＜0.05）. Logistic regression analysis showed that gender, age, smoking history, drinking history, family history of early onset coronary heart disease, hypertension history, total cholesterol, high density lipoprotein cholesterol, creatinine clearance, and type 2 diabetes mellitus history were adjusted, serum α-Klotho protein concentration was negatively correlated with acute myocardial infarction （OR＝0.995, 95% CI was 0.993～0.997, P＜0.05）. Conclusions Serum α-Klotho protein concentration in chronic stable angina pectoris group was higher than that in acute myocardial infarction group. The serum α-Klotho protein concentration was negatively correlated with acute myocardial infarction.