The invention discloses an automatic plate cutting machine. The automatic plate cutting machine comprises a cutting table. The cutting table is provided with a cutting set and a drive set controlling the cutting set to cut. The cutting set is detachably arranged on the drive set. The cutting set is provided with a plurality of linearly-arranged first hobbing cutters. A cutting groove used for cutting a lamp panel is formed below the first hobbing cutters. The cutting groove is internally provided with second hobbing cutters corresponding to the first hobbing cutters. The cutting table is further provided with a guiding groove and a limiting plate movably arranged in the guiding groove. The limiting plate is arranged on one side of the cutting groove. When the automatic plate cutting machine cuts lamp panels different in width, the position of the limiting plate on the guiding groove can be adjusted, rapidness and simpleness are achieved, and operation is easy.