The belt conveyor is a rubber conveyor belt with end (or no end) installed on the driving drum and driven drum at both ends of the conveyor. A number of balanced idlers and pallets are installed between the two rollers to support the weight of materials and conveyor belts. The driving roller, driven roller and idler are installed on the rack. The driving roller is driven to rotate by the driving device. The friction between the rotating drum and the conveyor belt makes the conveyor belt move, so as to achieve the purpose of transporting materials. In order to ensure proper tension of the conveyor belt, a tensioning device is also provided.