A composite middle trough with replaceable middle plates comprises a baffle ledge, a shovel plate ledge, the middle plates and a bottom plate, and is characterized in that the baffle ledge and the shovel plate ledge are arranged at the two ends of the middle plates, the middle plates are formed by the upper middle plate and the lower middle plate, the shovel plate ledge is formed by a shovel plate and a ledge body, the upper middle plate and the lower middle plate are connected in a welded mode, and the shovel plate and the ledge body are connected in a welded mode. When the middle plates are severely abraded and need repairing, what is only needed is to take down the upper middle plate and adopt and reweld a new abrasion-resistant plate, maintenance cost is lowered, and the service life of the composite middle trough is greatly prolonged; a high-strength abrasion-resistant plate is welded to an original cast ledge of the shovel plate, the abrasion loss, caused by coal cutter slipping boots, of the shovel plate is reduced, the service life of the shovel plate is greatly prolonged, and what is only needed is to replace the severely-abraded shovel plate with a new shovel plate.