The pathogenesis of coronary heart disease is closely related to inflammation. IL-1 beta is an effective target for anti-inflammatory treatment of coronary heart disease. Allopurinol is a drug used for treating hyperuricemia and gout for many years. Recently, allopurinol has been proved to inhibit the production of NLRP3 in monocytes and reduce the level of IL-1beta, resulting in the decrease of TNF-alpha, IL-6 and CRP. Thus, in this study, the investigators aim to evaluate the efficacy and safety of allopurinol sustained-release capsules on improving the stability of coronary plaque in patients with acute coronary syndrome treated by conventional standardized therapy by the single-center, prospective, randomized, double-blind and controlled methods, which would provide new strategies for the treatment of coronary heart disease.

Inclusion Criteria:

1. the people who understand and would sign the informed consent voluntarily;

2. Aged 18 to 80 years old;

3. hospitalized patients diagnosed as acute coronary syndrome in the past 1 months;

   1. hsCRP > 2mg/L;
   2. allopurinol allergy gene HLA-B5801 was negative.

Exclusion Criteria:

1. history of coronary artery bypass grafting;
2. allergy to allopurinol or any excipient;
3. administration of allopurinol or other uric-acid-lowering drugs within 7 days before randomization;
4. abnormal liver function (ALT >1.5 fold of the upper limit);
5. renal dysfunction (creatinine clearance rate <45 ml/min);
6. thrombocytopenia (PLT<100g/L);
7. gout patients;
8. uncontrolled infectious diseases in screening period;
9. Thyroid dysfunction, moderate to severe anemia (hemoglobin < 90g/L), systemic lupus erythematosus, malignant hematopathy, leukopenia, asthma, inflammatory bowel disease and other immune diseases were found during the screening period;
10. Non-steroidal anti-inflammatory drugs, steroid hormone, immunomodulatory and chemotherapeutic drugs not included in the study protocol should be taken for a long time during the study period;
11. the history of surgery or interventional operation within 6 months before the screening period;
12. patients with mental disorders such as anxiety or depression;
13. pregnant women, lactating women or women of childbearing age who did not use effective contraceptive measures ;
14. patients who participated in other clinical trials 3 months before the screening period;
15. the researchers judged that patients were not suitable for this clinical trials.

Revman