[Objective] This study evaluated the correlation between acute pancreatitis after endoscopic retrograde cholangiopancreatography(ERCP) and preoperative neutrophil to lymphocyte ratio(NLR),postoperative NLR,postoperative NLR,the ratio of postoperative to preoperative NLR,preoperative systemic inflammatory response index(SIRI),postoperative SIRI,the ratio of postoperative to preoperative SIRI.[Method] This retrospective study included 549 patients with common bile duct stones who underwent ERCP at our hospital from January 2021 to December 2023. The patients were divided into the post-ERCP pancreatitis(PEP) group(n=43) and non-PEP group(n=506).Relevant laboratory indicators, intraoperative ERCP procedures,basic patient information,and past medical history were collected. Differences in NLR and SIRI levels between these two groups were compared.Receiver operating characteristic(ROC) curve was used to assess the predictive value of each indicator for PEP.[Results] Among these indicators, the areas under the ROC curve (AUC) of the ratio of postoperative to preoperative NLR and the ratio of postoperative to preoperative SIRI after ERCP were both higher than 0.800. Specifically, the ratio of postoperative to preoperative SIRI exhibited a higher sensitivity (95.35%) and specificity (70.24%) than the other indicators.[Conclusions]The postoperative/preoperative NLR ratio and postoperative/preoperative SIRI ratio can be used as prognostic indicators of PEP.