The therapeutic effect of statins on the stabilization of atherosclerotic plaques has been affirmed. In recent years, the inhibition of matrix metalloproteinases (MMPS) of tetracycline drug doxycycline has attracted more and more attention. In this paper, we observed the effect of atorvastatin and doxycycline on exercise tolerance in patients with stable angina pectoris. The results showed that there was no significant difference in the clinical efficacy of the two groups and the effect on the exercise tolerance (P<0.05). There were 4 cases of mild gastrointestinal reaction in the doxycycline group and no other serious adverse reactions. The total effective rate of treatment in the doxycycline group was 93.3%. Doxycycline treatment significantly reduced the frequency of angina pectoris and the incidence of cardiovascular events, and the treatment effect was better. To sum up, we think doxycycline is a safe, cheap, therapeutic drug to stabilize plaque.