Objective To study the risk factors for duodenal injury caused by malposition of plastic bile duct stent for the treatment of biliary stricture. Methods Data of 1 408 patients with biliary stricture (2 607 procedures of plastic stent placement) who received plastic stent placement in Hangzhou First People''s Hospital from January 2017 to December 2021 were retrospectively analyzed and duodenal injury caused by bile duct stent malposition after placement was recorded. The patients were divided into two groups: the malposition injury group (n=23 procedures) and the non-malposition injury group (n=2 584 procedures). The differences in the baseline data and procedure-related condition between the malposition injury group and the non-malposition injury group were compared, and the independent risk factors for duodenal injury caused by bile duct plastic stent malposition were studied by using logistic regression analysis. Results A total of 2 607 procedures of plastic stent placement were performed in 1 408 patients with biliary stricture, and 23 cases of duodenal injury were caused by stent malposition. Logistic regression analysis revealed that a history of gastrointestinal surgery (OR=4.278, 95%CI: 1.332-13.737, P=0.015), a history of endoscopic sphincterotomy (EST) (OR=8.128, 95%CI: 2.382-27.738, P=0.001), and high-level bile duct stenosis (OR=4.457, 95%CI: 1.722-11.539, P=0.002), plastic stents with a length≥ 7 cm (OR=4.701, 95%CI: 1.708-12.938, P=0.003) and Christmas tree-shaped stent (OR=6.890, 95%CI: 1.540-30.830, P=0.012) were independent risk factors for duodenal injury caused by bile duct plastic stent malposition. Conclusion High-level bile duct stenosis, the use of plastic stents with a length≥ 7 cm and Christmas tree‑shaped stent, a history of gastrointestinal surgery, and a history of EST could increase the risk of duodenal injury caused by bile duct plastic stent malposition in patients with bile duct stenosis.