Abstract: Objective To explore the clinical efficacy of atorvastatin calcium in the treatment of diabetes mellitus complicated with atherosclerotic diseases. Methods From January 2017 to June 2018, a total of 221 diabetic patients with atherosclerotic diseases in hospitals the two authors worked were randomly divided into two groups. Among them, 113 patients treated by conventional medicine were selected as the control group, and 108 patients treated by atorvastatin calcium on the basis of conventional medicine were selected as observation group. The clinical effect was compared between the two groups. Results The levels of total cholesterol(TC), triglyceride(TG), low-density lipoprotein cholesterol(LDL-C)and fasting blood glucose(FPG)in the observation group were significantly lower than those in the control group(P<0.05). There was no significant difference in HDL-C between the two groups(P>0.05). The total effective rate of the observation group was significantly higher than that of the control group(P<0.05). The intima-media thickness of common carotid artery in the observation group was significantly thinner than that in the control group(P<0.05). The incidence rate of carotid plaque in the observation group was significantly lower than that in the control group(P<0.05). Conclusion Additional use of atorvastatin calcium on the basis of routine drug treatment is effective in treating diabetic patients with atherosclerotic diseases.