Selection of gearshift point plays an important role in the field of automatic transmission technology, which directly affects the vehicle dynamic and economic performance, etc. For stepped automatic transmission, it is generally believed that improving the fuel economy while not compromising the driveability is still a challenging research problem. And the traditional calibration method based on artificial experience widely used at home and abroad suffers from many issues, such as long development cycle, high cost, and real-time fault optimization between vehicle dynamic and fuel economy. In order to designing optimal gearshift strategies for conventional passenger vehicles equipped with stepped automatic transmission, in this paper, the analysis method of vehicle power demand was studied under different environment, different driving intention and different vehicle operating conditions. To obtain the highest efficiency of energy utilization is as the objective under the condition of meeting power demand and drivability. Dynamic programming (DP) method is used to solve the optimal gearshift decision sequence based on the simplified model of powertain system. NEDC and full throttle acceleration performance simulation were carried out respectively based on optimal dynamic shift schedule, optimal economic shift schedule and the proposed optimal gearshift strategy. The simulation result shows that the proposed optimal gearshift strategy can achieve the optimal tradeoff between the fuel economy and the driveability, which is adaptive to the vehicle dynamic characteristics. It is also observed that if applying the concept of vehicle power demand in the design of optimal gearshift strategy, the vehicle fuel economy can be improved without sacrificing the vehicle driveability.