Abstract: Objective To explore the correlations between the prognosis of patients with acute pancreatitis(AP)and blood urea nitrogen(BUN)as well as obesity related status(ORS). Methods The clinical materials of 300 AP patients were analyzed retrospectively. The correlations between BUN combined with ORS model and adverse prognostic factors of mild acute pancreatitis(MAP)as well as severe acute pancreatitis(SAP)were analyzed. Results BUN, body mass index(BMI)and glycosylated hemoglobin(HbA1c)were positively correlated with the incidence of adverse prognosis in AP patients(P<0.05). There was a significant positive correlation between the increase of BUN, fasting blood glucose(FBG)and the progression of AP(P<0.05). The incidence of complications, ratio of critical illness and death risk in AP patients were significantly increased when increased BUN combined ORS was existed. The evaluation effect of BUN combined with ORS model was better than that of single index model. Conclusion BUN combined with ORS model has a certain value in early evaluation of prognosis of AP patients, and the increase of related index value indicates a poor prognosis.