The large-scale application of connected automated vehicles(CAVs) provides new opportunities and challenges for the optimization and management of traffic conflict zones. In order to ensure the safety of vehicles and improve the operation efficiency of traffic flow in conflict areas, the concept of planning time interval is introduced. Then, with the average vehicle delay as the optimization objective and the minimum safety time interval of vehicles passing through the conflict zone is the constraint, a 0-1 mixed integer linear programming(MILP) model for the scheduling of vehicles entering the conflict zone is proposed. Finally, to study the influence of different traffic volumes on the proposed model, the numerical simulation experiments of different traffic scenarios are designed. The results show that the proposed model and algorithm can effectively reduce vehicle delays and fuel consumption compared with the vehicle schedule without optimization. The maximum reduction is 54.23% of vehicle delays and 34.36% of fuel consumption.