借助双层规划模型，从系统的角度探讨了区域公交车辆调度和购车计划之间的有机联系．根据该问题的特征将其等价转化为: 考虑车场容量、燃料及污染气体排放量等约束因素，如何在不同车辆数下构建每辆车完成班次的序列以完成所有班次，同时确定每辆车车型，追求车辆利用率最大和购车费用最少．利用遗传算法求解相应车辆数的上下层模型最佳解，比较所有可行方案确定最优解．最后，给出一个实例验证了模型和算法的正确性和有效性．

With the help of a bi-level programming model,the relationship between regional bus scheduling and its procurement scheme is explored from the viewpoint of system theory. According to proposed model’s characteristics,the above issue is equivalently converted into how to assign vehicles to cover all trips to maximize their utilization and determine the vehicle type to minimize the purchase expenses under different numbers of vehicles,where side constraints such as the depot capacity,the fuelling, the emission of polluting gases,etc.,are taken into consideration. The corresponding solutions of upper and lower model to different numbers of vehicles are obtained by using genetic algorithm and the optimal solution is selected by comparing all feasible schemes. Finally,the correctness and effectiveness of the proposed model and the algorithm are verified by an example.