Aim To compare and contrast two kinds of abdominal aortic aneurysm(AAA) model of rats, and thus to establish the foundation for the further study of AAA in vivo. Methods Commercially available porcine pancreatic elastase was Infused into the SD rat abdominal aorta, or orthotopic engraftment of guinea pig aorta was transplanted into the SD rat abdominal aorta. The patency, and macroscopic, microscopic morphologic and matrix metalloproteinase(MMP) changes that occurred in xenografts and the controls were compared postoperative 2 weeks or 4 weeks. Results There were AAA formation in 64 percent infused rats and 88 percent transplanted rats, without haemorrhage and intraluminal thrombus. In comparison to the AAA induced by elastase, the lesions of AAA walls after xenograft were more serious and the expression of MMP-2 and MMP-9 were remarkably increased. Conclusions Both of the methods may induce AAA,but xenograft model has higher stability and reliability.