Objective:To use Verifynow antiplatelet treatment monitor system(Verifynow), light transmission aggregometry(LTA) and PAC-1, CD62p tested by flow cytometry(FC) to study comparatively the antiplatelet function of clopidogrel.Method:①To draw 3mi blood samples of 71 patients who were selected from the inpatients or outpatients with acute coronary syndrome from 2011 March to 2011 July before they were treated and after that with two 3.8% sodium citrate anticoagulation vacutainers; We took out of 5pL blending whole blood from one of the two 3 mi samples to test the activity index of PAC-1 and CD62p by FC.