The invention discloses an automatic sandblasting spraying system and method for the interior of a box type body and belongs to the technical field of sandblasting spraying equipment. The system comprises the box type body to be coated, a sandblasting spraying robot and a control system body, through holes are formed in the side wall of the box type body, and transverse guide rails are arranged inthe through holes; longitudinal guide rails are arranged in the box type body; the crossing junctions between the transverse guide rails and the longitudinal guide rails are provided with track steering mechanisms, the sandblasting spraying robot is communicated with a feeding system, and the feeding system and the sandblasting spraying robot are both connected with the control system body; the sandblasting spraying robot is controlled by the control system body to move along the guide rails and enter the box type body through the transverse guide rails and adjusted through the track steeringmechanism to steer to the longitudinal guide rails from the transverse guide rails and conduct spraying on the interior of the box type body. According to the system and method, the sandblasting spraying robot can move along the guide rails arranged in the box type body to conduct sandblasting spraying on a sandblasting spraying surface, so that the labor intensity of workers is reduced, the sandblasting spraying efficiency and quality are improved, and the production cost is reduced.