Objective To investigate the pathogenesis of cerebral watershed infarction (CWI) through analyzing the appearance examined by Color duplex Imaging(CDI) and transcranial doppler (TCD).Methods One hundred and forty-two patients with CWI diagnosed by magnetic resonance imaging(MRI) were enrolled in the study group and 150 patients with acute cerebral infarction were enrolled in the control group.The results of CDI and TCD were retrospectively analyzed of the two groups.The vascular stenosis,plaque detection rate,plaque characteration,plaque scores,the cause of low blood volume,intracranial collateral circulation were compared between the two groups to investigate the pathogenesis of CWI.Results Among the 142 cases in the study group,there were 72 cases of severe stenosis and occlusion,21 cases of moderate stenosis,31 cases of mild stenosis and 18 cases without stenosis and there were 19 cases of severe stenosis and occlusion,41 cases of moderate stenosis,23 cases of mild stenosis and 67 cases without stenosis among the 150 cases in the control group.There were significant differences in the two groups (x2 =66.583,P =0.000).There were significant differences on the plaque detection rate between the two groups (80.99％ (115/142) vs 49.33％ (74/150),x2 =32.010,P =0.000).There were significant differences on the scores of plaque between the study group and the control group ((11.47 ± 3.78) points vs (6.57 ± 3.53) points,t =4.019,P =0.001).There were significant differences on the defined cause of low blood volume between the study group and the control group (54.93％ (78/142) vs 11.33％ (17/150),x2 =63.164,P =0.000).There were 50 patients had collateral circulation in the study group and 38 cases in the control group,there were no significant differences between the two groups (35.31％ (50/142) vs 25.33％ (38/150),x2 =3.381,P =0.066).Conclusion Angiostegnosis,microemboli from the unstable atherosclerosis plaque,lower perfusion on the basis of hypovolemia are all the pathogenesis of CWI.CDI combine with TCD can provide more information in vascular evaluation and treatment.