ObjectiveTo evaluate the value of 18FFDG PET/CT in the early diagnosis of secondary infection of severe acute pancreatitis (SAP).MethodsInfection group models of SAP SD rats were constructed with two types of bacteria (ATCC 25922 and ATCC 25923), control group model was constructed with saline solution. Complete blood cell count and serum amylase were measured at hour 0， 1， and 3  after modeling. After modeling for 3 hours，18FFDG PET/CT imaging was performed, then biological distribution, HE staining, and gram staining were performed to verify the results of PET imaging.Results18FFDG PET/CT imaging showed that rat models of two types of bacteria infection groups both showed radioactivity concentration in pancreas; target(pancreas) and nontarget (muscle) ratios(SUV) of Escherichia coli group, Staphylococcus aureus group, and saline group were 4.22+0.61，4.32+1.21，and 2.26+0.35 respectively. There was no statistical difference in the SUV of model animals between two types of bacteria infection group (P>0.05). The model of Escherichia coli infection group was statistically different from that of the control group model (P<0.01). Biological distribution was consistent with the result of PET imaging.Conclusion18FFDG PET/CT can be used as a detection method for early diagnosis of secondary infection of SAP.