Objective :To study the pathogenesis of acute severe pancreatitis(ASP).Methods: Minic models of rats with ASP were replicated. Retrograde injection of 3.5% sodium traurodeoxideocholic acid into them via pancreatic-bile duct with the catheters to abdominal aorta and peripheral blood vessel was performed. Then the concentrations of plasmic TXA2 and PGF1α were measured by RIA. The changes of pancreatic morphology were observed by macroscopy and microscopy, and microcirculation observed by intravital microscopy. Results :The concentration of plasmic TXA2 is rapidly deereased in abdomi- nal aorta perfusion. The changes of pancreatic morphology and microcirculation and the concentration of plasmic TXA2 is significantly different(P ＜ 0.01). Conclusion: The ob- stacle of pancreatic microcirculation is the cause and effect.