The midline type wafer type butterfly valve has the advantages of simple structure, small volume, light weight, good two-way sealing performance, quick opening and can replace the stop valve, gate valve and throttle valve. It is widely used in water supply and drainage, sewage discharge, power generation, petroleum, chemical industry, light textile, food and other fields. It is suitable for circulating water supply on the pipeline and economical traditional valves that the purchaser pays more attention to the valve price.