Objective: To investigate the relationship between the level of plasma homocysteine (Hcy) and carotid artery plaques in patients with acute cerebral infarction (ACI).Methods: 100 patients with ACI were collected in the affiliated hospital of Hainan Medical College from January 2012 to January 2014.Among them 50 patients of with hyperhomocysteine (Hhcy) were chosed for observe group, and 50 patients with normal homocysteine were chosed for control group.Carotid artery plaques in all patients were examined by CT angiography (CTA) and the level of serum Hcy were detected by enzymatic cycling assay.Result: Compared with the control group we found that the increased plasma Hcy level of the observe group was significantly associated with the number of plaque、 the type of plaque as well as the smooth of plaque surface.Conclusion: Hhcy has the close correlation with the characterastic of carotid artery plaques, and the evaluation on the level of plasma Hcy may have the significant meaning during the prevention and early diagnosis of cerebral infarction.