Objective：To explore expressions of platelet activator combined-1（PAC-1） and P-selectin（CD62p） in patients with acute cerebral infarction（ACI） at different degrees. Methods：Totally 287 patients with ACI from October 2008 to October 2011 were divid－ed into lacunar infarction group（n=76），small volume ACI group（n=125） and large volume ACI group（n=86）；50 health volunteer were served as control group. Levels of PAC-1 and CD62p were detected by flow cytometry. Results：Levels of PAC-1 and CD62p were increased in ACI group（46.9 mg/L，28.4 ng/L） than in control group（29.6 mg/L，10.3 ng/L）with significant differences（t=2.042，P=0.044；t=2.137，P=0.038）. Levels of PAC-1 and CD62p were significantly different among three groups（F=7.32，P=0.046；F=5.38，P=0.043）. Levels of PAC-1 and CD62p were significantly different between small volume ACI group（39.9 mg/L，24.5 ng/L） and la－cunar infarction group（45.9 mg/L，29.1 ng/L）（SNK-q＝4.417，4.129；P＝0.031，0.037）. Levels of PAC-1 and CD62p were significantly different between large volume ACI group（53.9 mg/L，33.8 ng/L） and small volume ACI group and lacunar infarction group（SNK-q＝4.216，4.022；P=0.039，0.042）. Conclusions：Significant expressions of PAC-1 and CD62p in patients with ACI can be used to detect the degrees of ACI and are of great importance in preventing and monitoring diseases development.