Objective To investigate the secondary prevention in acute coronary syndrome patients receiving percutaneous coronary intervention (PCI) during hospitalization and after discharge from Changhai Hospital. Methods The clinical data of patients with acute coronary syndrome undergoing PCI in Changhai Hospital from Jan 1^st. 2009 to Dec 31^st. 2011 were collected. The status of secondary prevention and drug therapies was analyzed at 1 month, six months and 1 year after discharge. Results A total of 238 patients with acute coronary syndrome receiving PCI were included in the present study. Smoking patients were forced to quit during hospitalization; the application rates of aspirin, angiotensin-converting enzyme inhibitors (ACEI)/angiotensin Ⅱ receptor blockers (ARB), β-blockers and statins among patients were 96.6%, 73.1%, 68.9% and 92.4%, respectively. At 1 month, 6 months and 1 year after discharge, the application rates of aspirin among the patients were 98.3%, 95.8% and 94.1%; of ACEI/ARB were 72.3%, 69.7% and 63.4%; of β-blockers were 68.1%, 62.2% and 52.1%; and of statins were 91.6%, 88.7% and 83.6%, respectively. At 1 month, six months and 1 year after discharge, the non-smoking rates were 86.4%,77.9% and 78.6% in male patients and 100%, 98.8% and 98.8% in female patients, respectively; the control rates of blood pressure were 93.3%, 95.4% and 94.3% and those of blood glucose were 98.3%, 96.2% and 97.5%, respectively. Conclusion The secondary prevention is satisfactory during hospitalization in acute coronary syndrome patients undergoing PCI, but the situation gradually worsened after discharge; therefore efforts should be made to strengthen the follow-up and health education of the patients so as to reinforce secondary prevention for coronary heart disease.