Objective To compare the results of transcranial Doppler(TCD) and computed tomography(CT) in the diagnosis of acute cerebral infarction(ACI).Methods Total 160 patients with ACI confirmed by brain CT from August 2008 to July 2012 in our hospital were divided into three groups: large infarction,small infarction and lacunar infarction group.TCD was performed in all patients to observe the rate of abnormality.Results The total abnormal rate of TCD examination in ACI patients was 71.88%,with a rate of 91.38% in the large infarction group,61.82% in the small infarction group and 59.57% in the lacunar infarction group.The abnormal rate of TCD in the large infarction group was more obviously.The difference among the three groups was statistical significant(P 0.05).Conclusion The cerebral artery hemodynamic parameters can be directly got by TCD examination which will be an important auxiliary diagnostic method for acute cerebral infarction especially the large area cerebral infarction.