Abstract: Objective To observe the correlation between smoking and blood lipid level and degree of coronary artery lesions in patients with acute myocardial infarction. Methods Totally 129 patients with acute myocardial infarction were studied. According to the internationally recognized smoking index classification method, the above patients were divided into 4 groups as grade 0 (43 cases), grade 1 (33 cases), grade 2 (31 cases) and grade 3 (22 cases). The changes of triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) of patients with different smoking indexes were compared. At the same time, Judkins method was used to implement elective coronary angiography via femoral artery. The number of coronary artery lesions in patients with different smoking indexes was observed. Results TC, TG and LDL-C of patients in the grade 0-3 groups showed an increasing trend (r=0.747, 0.914,0.833, respectively, P<0.05) and TG of patients in grade 3 group was significantly higher than that of patients in the grade 0 and 1 groups, while LDL-C was significantly higher than that of patients in grade 0 group (P<0.05).The prevalence of three-vessel lesion of patients in grade 1, 2 and 3 groups was significantly higher than that of patients in grade 0 groups,respectively(P<0.05/6). The prevalence of three-vessel lesion showed an increasing trend with increasing smoking indexes(r=0.863, P<0.05). Conclusion Smoking can affect the blood lipid level in patients with acute myocardial infarction,which needs more clinical attention.