Abstract: In order to improve on the acceleration characteristics and driving range of the electric bus, hybrid operation with battery and ultracapacitor are accepted. According to the powertrain design scheme, a new method to design battery and ultracapacitor is put forward, the relationship of battery pack's capacity to acceleration time and range and the design approach of ultracapacitor based on its discharge time are established. Experimental results on electric bus BFC6100-EV showed that the acceleration time of 0～60 km/h is reduced 9 s and the range reaches 306 km, accordingly proved this method is feasible and valid.