The performance of batteries, in their lifespan, efficiency, and safety, is affected by the uniformity of temperature within the batteries. Therefore, battery thermal management is crucial in the development in electric vehicles. In this paper, a novel battery pack with a wedge-shaped runner is proposed. A 2-dimensional computation fluid dynamics model was built, and the battery pack structure was optimized, including changes in the positions of the inlet/outlet, the width of the wedge-shaped flow path, the inclination angle of the batteries, and the clearance between the batteries. Finally, the structure is studied and simulated under different ambient temperature and air velocity. The results indicated that the temperature distribution exacerbated with the increase of the inlet temperature and improved with the increase of the inlet velocity. Furthermore, the inlet temperature had little result on the temperature consistency, and the inlet velocity had a greater result on the temperature consistency. The conclusions drawn in this research are expected to play the part of good guidance for the future design of a new battery thermal management system.