Objective:To explore clinical therapeutic effect and safety of diltiazem treating coronary artery spasm. Methods:A total of 100 patients with coronary artery spasm were selected in our hospital.According to number ta-ble method,they were randomly and equally divided into routine treatment group (n=50,received,lipid regulation and expanding coronory artery etc.)and diltiazem group (n=50,received diltiazem pumping based on routine treat-ment).Clinical and ECG therapeutic effect,changes of blood lipids,nitric oxide (NO)and endothelin-1 (ET-1) levels before and after treatment and safety were compared between two groups.Results:(1 )Compared with rou-tine treatment group,there were significant increase in total effective rates of clinical effect (60.00% vs.94.00%) and ECG (62.00% vs.92.00%)in diltiazem group,P<0.01 both;(2)Compared with before treatment,there were significant improvements in all ECG indexes,heart rate and blood pressure in two groups after treatment,and those of diltiazem group were significantly better than those of routine treatment group (P<0.05 all);(3)Com-pared with before treatment and routine treatment group,there were significant improvements in blood lipid levels in diltiazem group after treatment (P<0.05 all);(4)Compared with before treatment and routine treatment group,there was significant rise in NO level [(95.17±19.99)μmol/L,(95.17±21.22)μmol/L vs.(106.71± 22.38)μmol/L]and significant reduction in ET-1 level [(64.09±16.29)ng/L,(59.98±14.28)ng/L vs.(44.91± 6.38)ng/L]in diltiazem group after treatment (P<0.05 all);(6)During treatment,there were no adverse reac-tion in both groups.Conclusion:Diltiazem based on routine medication possess significant therapeutic effect and high safety for treating coronary artery spasm,which is worth extension in clinic.