Electric vehicle, battery box body thereof, and battery box

The invention relates to an electric vehicle, a battery box body thereof, and a battery box. A cooling structure is arranged on a bottom plate assembly of the battery box and comprises two or more layers of hollow channels which are formed at intervals in vertical direction, the upper hollow channel forms a cooling channel used for allowing cooling liquid to circulate, and the lower hollow channelis filled with a thermal insulation material; and in the operating process of the battery box, the cooling liquid in the cooling channel can cool a battery module in the battery box. Meanwhile, the lower hollow channel is filled with the thermal insulation material, thus a thermal insulation layer is formed, heat in the external environment is prevented from being transmitted into the battery box, through the thermal insulation material, the heat in the external environment is prevented from influencing the cooling liquid, and the problem that properties of the battery box are influenced accordingly is solved; and after the bottom plate assembly is filled with the thermal insulation material, the weight of the bottom plate assembly can also be lowered obviously, hollow structures are arranged, and thus the structural strength of the bottom plate assembly can further be ensured.