This research proposes a new concept of electric bus with adjustable interior modules. By installing different modules, it can adjust both its internal layout and battery capacity spontaneously to make itself resemble an electric city bus or an electric regional bus when it is needed. It makes use of difference between peak times of regional lines and city lines so that it provides the same service as one city bus and one regional bus can do. This research firstly verified the timetable feasibility of this adjustable electric bus. It turns out that one vehicle is able to operate both city and regional bus network with observable resilience, reduction of minimum vehicle number and saving of electricity consumption. However adjustable BEB is limited by its high purchasing and operation cost, making it not highly profitable in a whole concession period. Accordingly, this research suggests low-entry utility electric bus is the more reliable and cost-efficient choice to carry out combined network operation.