The invention belongs to the technical field of rear projection splicing, and particularly relates to a rear projection box heat dissipation structure and a rear projection splicing wall heat dissipation system with the same. According to the rear projection box heat dissipation structure, a projector system is arranged in a rear projection box and is correspondingly provided with an air inlet and an air outlet, wherein a side face of the rear projection box is provided with a cold air groove, and the opposite side face of the rear projection box is provided with a hot air groove; the cold air groove is provided with a cold air port which is communicated with the interior of the rear projection box; and the hot air groove is provided with a hot air port which is communicated with the interior of the rear projection box. The cold air groove and the hot air groove are arranged in the opposite side faces of the rear projection box, so that normal reflection and projection of a grating by a picture output by the light through a projector in the rear projection box can be guaranteed, the internal space of the rear projection box is not occupied, and the heat dissipation space of the projector system is guaranteed; and the rear projection box heat dissipation structure is arranged on the side face of the rear projection box and is far away from the projector system, so that a good heat dissipation effect is achieved, uniform variation in brightness of a light source can be guaranteed, and attenuation specification and life specification can be met.