Objective:To explore the prognostic value of modified lymph node ratio(mLNR)and to construct a model to predict cancer-specific survival(CSS)in patients with non-muscle-invasive bladder cancer(NMIBC)after radical cystectomy(RC).Meth-ods:Eligible NMIBC patients were randomized in a 7∶3 ratio into a training group(n=651)and a validation group(n=280).Univa-riate and multivariate Cox regression analyses were used to screen for independent predictors by stepwise regression and to check for multicollinearity between variables,and then nomograms predicting CSS were created and validated.The developed risk classification system was tested by Kaplan-Meyer survival analysis and log-rank test.Results:Age,marital status,N-staging,radiotherapy and mLNR were independent prognostic factors for CSS in patients with NMBIC.The nomogram C index for the training cohort was 0.706(95％CI:0.661～0.751).In the training cohort,the AUCs for predicting 1,5,and 10 years CSS were 0.799,0.736,and 0.732,respectively.In the validation cohort,the AUCs for predicting 1,5,and 10 year CSS were 0.543,0.703,and 0.668,respectively.Conclusion:The mLNR is a new independent prognostic indicator,and the prognostic model developed based on it predicted 1,5,and 10 year CSS slight-ly better than the AJCC staging system,which is conducive to the enrichment of prognostic indicators for cancer.