The invention relates to the technical field of conveyors, and discloses a telescopic type belt conveyor comprising a fixed box. A baffle is fixedly installed between the top and the bottom of an inner cavity of the fixed box. A first hydraulic cylinder is fixedly installed on the left side of the baffle. A first movable box with one end penetrating through and extending to the left side of the fixed box is fixedly installed on the left side of the first hydraulic cylinder. The first movable box is movably connected with the fixed box. A second hydraulic cylinder is fixedly installed on the right side wall of an inner cavity of the first movable box. A second movable box with one end penetrating through and extending to the left side of the first movable box is fixedly installed on the left side of the second hydraulic cylinder. The second movable box is movably connected with the first movable box. A connection shaft is fixedly installed between the front side wall and the rear side wall of an inner cavity of the second movable box. The telescopic type belt conveyor is simple in overall structure, the online efficient weighing work of goods is achieved, the time required by objectweighing is shortened, manpower required by object weighing is reduced, the work efficiency is improved, use is facilitated, and the user experience feeling is improved.