Aim To explore the relationship between Id1 expression in neointima and vascular neointima hyperplasia. Methods The model of carotid arteries injured was established by catheter in mice. Kunming mouse were randomly divided into 4 groups:control group,groups of 7 day,14 day and 28 day after the injury. The vascular morphology was analyzed by HE dying. The expression of Id1 mRNA was measured by reverse transcriptase PCR,and the protein of Id1 was assessed by Western blotting and immunohistochemistry. Results The ratio of intima area to media area (IA/MA) was significantly increased in 7 day after vascular injury than that in control group (P><0.05),and further to increase on 14 day and 28 day after injury (P><0.01). The expression of Id1 mRNA in experimental groups was significantly increased than that in control group (P><0.05). The Id1 mRNA was significantly increased on 14 day than that in 7 day and 28 day after vascular injury (P><0.05). The expression of Id1 protein was similar with the expression of mRNA. The low level Id1 was detected in the uninjured vessel by the immunohistochemistry. However,Id1 staining was increased only in the medium at 7 days,enhanced significantly in medium and neointima at 14 days. However,Id1 staining was decreased at 28 days. Conclusion The Id1 expression was in the dynamic changes in the process of vascular neointema hyperplasia after vascular endothelial injury,and it maybe play a role in the neointema hyperplasia after vascular injury.