Objective Based on"the surveillance,epidemiology,and end results"(SEER)data-base,we constructed a nomogram model for predicting cancer-specific survival time(CSST)in patients with T2 stage gallbladder cancer.Methods Clinical data on 486 patients with T2 stage gallbladder cancer between 2018 and 2020 were retrospectively collected from the SEER database.The cohort comprised 147 male and 339 female patients with the age at diagnosis of(70±13)years.Clinical information including age,gender,tumor size,tumor stage,surgical type,number of lymph node dissection,postoperative treat-ment,and patients prognosis were extracted from the SEER database.We analyzed the factors influencing CSST in patients with T2 stage gallbladder cancer using Cox risk-proportional regression.The nomogram model was constructed based on independent risk factors obtained from multivariate Cox regression analysis,and the area under curve(AUC)of receiver operating characteristic curves(ROC)were used to evaluate the predictive accuracy of the nomogram model,while calibration plots,decision curve analysis,and clinical impact curves were used to evaluate the model's practicality and effectiveness.Results The results of multi-variate Cox regression analysis showed that patients with tumor size≥30 mm(HR=1.775,95%CI:1.123-2.806),AJCC stage ⅢB(HR=6.083,95%CI:2.961-12.495),1-3 lymph node dissection(HR=6.139,95%CI:2.876-13.106),no postoperative chemotherapy(HR=1.743,95%CI:1.096-2.771)had a higher risk of short CSST(all P<0.05).A nomogram model for predicting CSST was con-structed based on the above risk factors,and the AUC of the ROC of which for predicting 1-year and 2-year CSST in patients with T2 stage gallbladder cancer was 0.778 and 0.696,respectively.Calibration plots demonstrated excellent collinearity between predicted and actual probabilities.Decision curve analysis and clinical impact curves confirmed high net benefit and clinical validity of the nomogram model.Conclusions The tumor size ≥30 mm,AJCC stage ⅢB,1-3 lymph node dissection and no postoperative chemotherapy are risk factors for short CSST in patients with T2 gallbladder cancer.The nomogram model based on the above risk factors have excellent performance in predicting CSST in patients with T2 stage gallbladder cancer.