To explore the changes of the antigen expression and the biomechanical characteristics of blood vessel in Banna little ear pig before and after trypsin treatment, and provide data for xenotransplantation and pig vessel using for tissue engineering. Geometric morphology and microstructure of pig cartoid artery were stuided quantitatively by histologic method and computer image analysis. The relationship between pressure and diameter was observed at different period of time before and after trypsin treatment. Affinity-immunohistochemistry assay was conducted to detect the expression of xenoantigens (alpha-Gal). The results showed that alpha-Gal antigen is only expressed in vascular endothelial cellsouly. There is no significant difference in blood vessel compliance. These demonstrate that the antigenicity of pig carotid artery is significantly reduced, however, the mechanical characteristics did not change significantly. We suppose that pig vessels treated by trypsin can be used as the substrate material for vascular tissue engineering.