The utility model discloses a constructing rack device for assisting prestress tension applied to projects such as railways, highways, industrial buildings, water conservancy, energy sources and ground anchorage. The constructing rack device is composed of an outer die carrier, an inner die carrier, an anchor pedestal, a tension anchor and a pulley subassembly, wherein each of the outer die carrier and the inner die carrier is composed of scaffold steel pipes; the inner die carrier is arranged inside the outer die frame; the anchor pedestal is arranged on the inner die carrier; the tension anchor is arranged on the anchor pedestal; the pulley subassembly is connected onto the outer die carrier; a universal rotating wheel is arranged at the bottom part of the outer die carrier; the anchor pedestal is composed of a square timber, a rebar mesh and a rebar guardrail; the rebar mesh is arranged on the square timber, and the rebar guardrail is arranged on the rebar mesh. The rack device is simple in structure, and convenient to operate, and utilizes local materials. The engineering practice shows that the tension speed is fast; construction is safe, and the construction cost is reduced after the rack device, disclosed by the utility model, is used.