Objective To explore the effect of renal microcirculation following severity acute pancreatitis (SAP) on renal injury and to explore the protection effect of urokinase on them. Methods A total of 192 Wistar rats were randomized divided into normal control group, SAP group, and urokinase group, then rats of 3 groups were sub-divided into 2, 6, 12, and 24 hours group, each group enrolled 16 rats. Of the 16 rats in each subgroup, 8 rats underwent blood flow of renal test, other 8 rats were sacrificed to get blood samples and to perform histopathological examination. The rat models of SAP were established by retrograde injecting with 5% sodium taurocholate into the cholangiopancreatic duct. Radioactive biomicrosphere technique was used to measure the blood flow of renal, levels of plasma thromboxane B2(TXB2) and 6-keto-prostaglandin F1α (6-Keto-PGF1α) were tested by the TXB2 kit and 6-Keto-PGF1α kit, and histopa-thological changes of renal tissues were observed by using HE staining. Results Compared with normal control group at the same time point, the blood flow of renal were lower (P<0.05), activity ratio of TXB2 to 6-Keto-PGF1α were higher(P<0.01), and the histopathological injury were worse (P<0.01) in rats of SAP group and urokinase group. Compared with SAP group, the blood flow of renal at 2, 6, and 12 hours in urokinase group were higher (P<0.01), the activity ratios of TXB2 to 6-Keto-PGF1α were lower (P<0.01), and the histopathological injury were lighter (P<0.05) in all the 4 time points of urokinase group. Conclusions The renal microcirculation dysfunction and increase of activity ratio of TXB2 to 6-Keto-PGF1α may play an important role in renal injury following SAP in early stage. Urokinase can protect the renal from such injuries.