Abstract: AIM To observe the prognostic effect of fractional flow reserve(FFR) guided interventional therapy in non-ST elevation acute coronary syndrome(NSTE-ACS) patients with borderline lesions. METHODS NSTE-ACS patients with coronary stenosis(50-70% of the lesions) confirmed by coronary artery angiography(CAG) in our hospital were randomly divided into CAG group and FFR group. Patients were followed for 12 months and the rates of recurrent angina pectoris and major adverse cardiovascular events(MACE) were compared between groups. RESULTS The rates of recurrent angina and MACE events in FFR group were lower compared with the CAG group. CONCLUSION FFR guided PCI treatment better alleviates the symptoms of patients with angina pectoris, reduces MACE events and improves the prognosis of patients with NSTE-ACS critical lesions.