Objective;To investigate the effects of regional arterial infusion of urokinase (LAI) on the pancreaticmicrocirculation in rats with severe acute pancreatitis(SAP). Methods;Rats were divided into 4 groups: sham operation(A) group, SAP(B) group, urokinase LAI(C) group and normal saline LAI(D) group. Pancreatic blood flow was measured by laser Doppler instrument, pancreatic microvascular permeability was determined by measurement of extravasation of Evans Blue, and pathological changes of pancreas were observed. Results;(1)Pancreatic blood flow(PBF):at 1h and 3h,PBF in A group was significantly higherthan that in B,C,D group(all P<0.05),but there was not significant difference between B and D group(P>0.05); however,PBF in C group was significantly higer than that in B and D group(P<0.05). (2)Extravasation of Evans Blue:in normal pancreat tissue was（149.11±17.93）ug/g， which was significantly lower than that in B,C,D group((all P>0.05),but there was not obvious difference betweenB,C,D group(all P>0.05).(3)Pathological score of C group at 1h and 3h was significantly higher than the A group(P<0.05), but was significantly lower than that of B and D group(P<0.05); howerer there was not significant difference between B and D group(P>0.05). Conclusions;UrokinaseLAI can improve the microcirculation of rats with SAP, but can not completely prevent the pathologicalchanges of SAP.