The invention relates to a battery box of an electric vehicle. The battery box comprises a box body with an opening in the upper end, wherein the box body comprises an outer box and an inner box; one side of a box cover is rotationally connected with that of the box body, and the other side of the box cover is connected with that of the box body through a lock catch; a plurality of limiting blocks are arranged on each side of the inner box; a battery is arranged in the box body; a heat dissipation plate is arranged between the outer box and the inner box; an anti-theft alarm, a temperature alarm and a GPRS (general packet radio service) positioning device are arranged on the bottom surface of the box cover and connected with the battery respectively. The battery box of the electric vehicle solves problems that the battery is likely to slide in the battery box, easy to steal, poor in heat dissipation and easy to burn out.