【Objective】In order to study the joint optimization problem of metro passenger-freight cotransportation and timetable under the train-dedicated mode, the relationships between trains, demands and potential spacetime trajectories are reconstructed and an integer linear programming model is formulated instead of the traditional nonlinear programming model.【Method】The objective function of this model includes the number of freight trains in use, the waiting time of passenger demand as well as the detention time of freight demand. The restriction conditions to be met mainly include the flow balance constraints of passenger and freight demands, the capacity constraints of passenger and freight trains, the longest waiting time constraint of passenger demand and the longest detention time constraint of freight demand. By relaxing the integer-type variables of passenger and freight flows, the primal model could be equitably transformed into a mixed integer programming model, which can improve the solving efficiency of the model. Taking the original Batong Line of Beijing Metro as the background information, a series of numerical examples were designed and then solved by commercial solver Gurobi.【Result】The experimental results show that Gurobi can solve the relaxation model faster than the primal model; and compared with the original timetable, the optimized timetable can reduce the generalized cost.【Conclusion】The proposed method can not only meet the needs of subway passenger and freight cotransportation in the split mode, but also effectively control the influence of metro freight on passenger demand under this mode.