The invention discloses an automatic door device of a casting and welding machine, which comprises a fixed door frame mounted on the front side of a frame of the casting and welding machine and a movable door frame in sliding connection with the fixed door frame through a sliding track device, wherein a protection partition plate is arranged on the movable door frame, a lifting cylinder for driving the movable door frame to slide up and down is arranged on the frame of the casting and welding machine, and the lifting cylinder is controlled by an electrical control box arranged on one side of the frame of the casting and welding machine. The automatic door device of the casting and welding machine is simple in structure, flexible to operate, convenient to open and close and small in occupied space, and can effectively ensure working safety of casting and welding operation staff.