Abstract: OBJECTIVE To investigate the level of plasma neutrophil extracellular traps（NETs） in pancreatitis patients combined with infection and its relationship with the severity and prognosis of the disease. METHODS Total of 202 patients with acute pancreatitis and bacterial infection who were admitted to the the First Affiliated Hospital of Nanyang Medical College between Dec. 2016 and Jun. 2019 were recruited and divided into the infection group. Another 100 patients with acute pancreatitis and without infection were in the acute pancreatitis group, and 50 healthy adults were in the control group. Pathogenic bacteria in the infected patients were detected, and levels of plasma NETs in all groups were determined by fluorescence spectrophotometry. Data such as peripheral blood white blood cell count, neutrophils, procalcitonin（PCT）, C-reactive protein（CRP）, acute physiology, chronic health evaluation II（APACHEII） scores and sequential organ failure assessment（SOFA） scores were collected. Patients in the infection group were followed up and their 28-day mortality rates were statistically analyzed. RESULTS A total of 234 strains of pathogenic bacteria were isolated from 202 pancreatitis patients combined with infection, including 152 strains of Gram-negative bacteria（64.96%）, 72 strains of Gram-positive bacteria（30.77%） and 10 strains of fungi（4.27%）. The descending order of plasma NETs levels were the infection group, the pancreatitis group and the control group in turn（P＜0.05）. The levels of white blood cell count, the proportion of neutrophils, serum PCT and CRP, APACHEII score and SOFA score in the infection group were significantly higher than that in the pancreatitis group（P＜0.05）. Plasma NETs level, the proportion of neutrophils and serum PCT level were positively correlated with APACHEII score and SOFA score（P＜0.05）. Plasma NETs levels, white blood cell count, the proportion of neutrophils, serum PCT and CRP level, APACHEII score and SOFA score in the death group were significantly higher than that in the survival group（P＜0.05）. ROC curves showed that the areas under curve of plasma NETs level, white blood cell count, the proportion of neutrophils, serum PCT and CRP levels for predicting the prognosis of patients were 0.855, 0.649, 0.683, 0.828 and 0.670, respectively. CONCLUSION Pancreatitis patients combined with infection had elevated plasma NETs levels which were related to the severity and the prognosis of the disease. The plasma NETs level can be used to evaluate the prognosis of the disease and can be helpful to the treatment.