Objective:To evaluate the association between preoperative systemic inflammatory response index (SIRI) and postoperative complications in patients with obstructive colorectal cancer (OCCRC) undergoing self-expanding metal stent (SEMS) as a bridge to surgery, and to develop and assess a predictive model for postoperative complication risk based on key clinical factors.Methods:Clinical data of 104 OCCRC patients who underwent radical surgery following SEMS placement at the Department of Colorectal Surgery, the First Affiliated Hospital of Fujian Medical University, from August 2019 to December 2024 were retrospectively analyzed. Logistic regression was used to identify independent predictors of postoperative complications, and a nomogram was constructed to evaluate predictive performance.Results:The optimal SIRI cutoff value was determined by ROC analysis, and patients were classified into low- ( n=51) and high-SIRI ( n=53) groups.Postoperative complications occurred more frequently in the high-SIRI group than in the low-SIRI group (39.62% vs 13.73%, χ2=8.86, P=0.003). Multivariate logistic regression identified age ( OR=1.05, 95% CI: 1.01-1.09, P=0.027), intraoperative blood loss ( OR=4.45, 95% CI: 1.56-12.75, P=0.005), and high SIRI ( OR=3.73, 95% CI: 1.29-10.83, P=0.015) as independent predictors. The nomogram incorporating these variables showed good predictive ability with an AUC of 0.736. Conclusions:Preoperative elevated SIRI is an independent risk factor for postoperative complications in OCCRC patients treated with SEMS as a bridge to surgery. A nomogram combining SIRI, age and intraoperative blood loss provides effective risk stratification.