Aim To observe the changes of serum level of the CD62p, CD63, glucose protein (GP)_b/Ⅲ_a which indicated the platelet activity and serum levels of von willebrand factor (vWF), flow-mediated dilatation (FMD), endothelium 1 (ET-1), nitrogen oxide (NO) which indicated function of vascular endthelium after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS). Methods The expression levels of CD62p, CD63, GP_b/Ⅲ_a and vWF, ET-1, NO and FMD were examined in brachial artery at the same time using ultrasonography from before treatment, immediate and 24 hours after treatment of PCI in 60 patients with ACS and compared with control. Results The ACS patients' blood CD62p, CD63, GP_b/Ⅲ_a levels increased significantly compared with healthy control group and stable angina pectoris (SAP) (p<0.05 or p<0.01), and those of post PCI immediate group increased significantly than pre-PCI group ( p<0.01). There were no significant difference (p>0.05) between post-PCI 24 hour group and pre-PCI group. The blood vWF and ET-1 levels of ACS patients increased significantly (p<0.01), FMD and NO decreased significantly (p<0.05 or p<0.01) compared with healthy control group and SAP group. The vWF and ET-1 levels of post-PCI immediate group increased significantly (p<0.05 or p<0.01), FMD and NO decreased significantly (p<0.05) compared with pre-PCI group, and vWF and FMD had significant difference (p<0.05) between post PCI 24 hour group and pre-PCI group. While ET-1 and NO had no significant difference (p>0.05) between post-PCI 24 hour group and pre-PCI group. Conclusion Platelet activation and vascular endothelial cell impairment played an important role in the occurrence and development of ACS. The vascular endothelium function was impaired and platelet were obviously activated to some extent in patients with ACS after PCI immediate.