Abstract: In order to improve the efficiency of bogies of railway transit and to reduce the maintenance cost,it is necessary to optimize the maintenance scheduling.According to the renewal reward theory,the objective of this study is the minimization of average maintenance cost per unit cycle for safe operation.On the basis of the delay time theory,this study develops an optimized maintenance scheduling model for the bogies of railway transit.Based on the failure records and preventive maintenance inspection data,this study develops the delay time distribution function related to maintenance scheduling and a maximum likelihood method is used to estimate model parameters and the optimal maintenance period. Finally,this model is applied to test a subway maintenance plan as a case study.A comparative analysis between optimi-zation results and existing maintenance scheduling is carried out and used to validate the model.The results show that the maintenance cost of the bogies of the rail transit vehicles reduces by 23% when the optimized delay function is applied and combined with the group preventive maintenance.This study may serve as a reference for planning maintenance schedu-ling of rail vehicle bogies.