BAOYI butterfly valve for expansion joint which is composed of the central-line butterfly valve as the basic component and the expansion device can compensate the pipeline installation length caused by thermal expansion and contraction. With the features of convenient maintenance and installation, the product can be used for old pipeline reconstruction. The product design can meet such relevant standards as API 609 and EN 593. Generally, the product can be applied in the pipelines for petroleum, gas, chemical product, food, medicine, electric power, water supply and drainage to adjust flow rate and cut off medium.