The invention discloses an electric vehicle power battery box with efficient thermal dissipation. The electric vehicle power battery box comprises a battery box body, wherein multiple side-by-side grids used for placing single batteries are arranged in the battery box body; the grids and the single batteries form power battery modules; the grids are machined and shaped by thermal conducting aluminum sheets; preferably, the power battery modules are mounted in two layers in the battery box; the lower layer power battery module is mounted on the bottom plate of the battery box; the bottom surface of the upper layer power battery module and a thermal conducting apparatus are sealed; and a thermal conducting channel between the bottom surfaces of the power battery modules and the battery box is established through the thermal conducting apparatus. According to the electric vehicle power battery box provided by the invention, the single batteries are placed in the side-by-side grids; the thermal environments of each single battery are same; and therefore, the temperature differences of the single batteries in the battery box is reduced, and high thermal dissipation efficiency is achieved.