A composite throttle valve. The invention relates to the improvement of the structure of the sewage and waste water catchment device. It can control the amount of sewage inflow to a single well to avoid excessive sewage flowing into the treatment plant and causing the treatment plant to run overloaded. It includes a well body located below the ground and connected to the sewage pipe, and also includes a flap door, a cable, a suspension pulley and a counterweight buoy; the flap door is movably connected to the sewage pipe mouth; The upper part of the wellhead in the body; the cable is wound on the suspension pulley, one end of the cable is connected to the lower edge of the flap door, and the other end of the cable is connected to the counterweight buoy. The present invention is provided with flap door in the well body, and it itself has the function of preventing excessive water from entering the pipeline. In the present invention, it is required to be in the open state under normal conditions, so the present invention also adds a counterweight buoy that can make it in the open state. Under normal circumstances, some domestic wastewater flows through the well body and flows into the sewage treatment plant through pipelines for centralized treatment.