Objective To analyze the risk factors of short-term re-obstruction after plastic stent placement by endoscopic retrograde cholangiopancreatography (ERCP) in patients with hilar malignant biliary obstruction.Methods A retrospective study was performed on clinical data of 93 patients with hilar malignant biliary obstruction who underwent ERCP biliary plastic stent placement from January 2015 to January 2024. Understanding the effects of general information, clinical characteristics, operative-related factors, and laboratory-related indicators on postoperative short-term re-obstruction. The dependent variable was whether biliary stent re-obstruction in short-term after operation, univariate and multivariate Logistic regression analysis were used to analyze the risk factors for the patients with hilar malignant biliary obstruction occurred re-obstruction in short-term after ERCP plastic stent placement.Results Among the 93 patients, 49 patients had short-term recurrent biliary stent obstruction after plastic stent placement by ERCP and the recurrence rate was 52.7%. Univariate analysis showed that gender, types of malignant biliary strictures, preoperative cholangitis, no drainage before operation and endoscopic sphincterotomy (EST) during ERCP plastic stent placement, location of stent placement, fever within 24 h after ERCP plastic stent placement, the decrease less than 50% of total bilirubin (TBiL) at 2 weeks after operation, the decrease less than < 50% of γ-glutamyl transpeptidase (GGT) at 2 weeks after operation, GGT and alkaline phosphatase (ALP) by less than 50% at 2 weeks after operation were potential risk factors affecting for short-term re-obstruction after ERCP plastic stent placement in patients with hilar malignant biliary obstruction. Multivariate analysis showed that, no drainage before operation (OR＾ = 5.738, P = 0.013), preoperative cholangitis (OR＾ = 5.347, P = 0.025) and place stents on the left or on the right （OR＾ = 6.739，P = 0.014；OR＾ = 9.719，P = 0.005）were independent risk factors for short-term re-obstruction after ERCP plastic stent placement.Conclusion No drainage before operation, preoperative cholangitis, place stents on the left or on the right are independent risk factors for short-term re-obstruction after ERCP plastic stent placement in patients with hilar malignant biliary obstruction.Early identification of risk groups and timely intervention of risk factors in clinical practice are of great significance for the prevention of short-term re-obstruction after ERCP plastic stent placement in such patients.