An all-terrain vehicle and a body thereof are provided. The body includes: a vehicle frame and a seat frame. The vehicle frame includes a front part, a middle part, and a rear part, connected in sequence. The rear part is provided with a power compartment for accommodating a power train. The front part includes a lower mounting frame and an upper support frame, the lower mounting frame is connected to the middle part, and the upper support frame can be detachably connected to both the lower mounting frame and the middle part. The seat frame is detachably arranged in the middle part and defines, with a bottom of the middle part, a mounting space for a plurality of components.