Three-bar shut-off butterfly valve has a valve body and a configured valve plate and a main shaft penetrating the valve body. On the main shaft are mounted an active rod connected with the central supporting plate of the valve plate through pins and a fixed rod symmetrically set up on both sides of the active rod. The rear end of the fixed rod is hinged to the valve body. The front end of the fixed rod is connected with the driven rod though pins. The other end of the driven rod is connected with the supporting plate on the valve plate side through pins. There is a stuffing sealing structure set up at the joint section of the main shaft and valve body. The main shaft bearing is set up at the outer side of the sealing structure. The actuating device that is composed of a hydraulic cylinder and a crank is set up at the valve body side. Sanitary butterfly valve employs the principle of four-bar mechanism to achieve opening and closing. When the valve plate contacts with and leaves the sealing, it makes horizontal movement without friction, so the valve has a long service life. Various hinge points in the rod are equipped with high-temperature self-lubricating bearings, which ensure flexible running and no jamming in high-temperature working conditions. The stopper sealing is set up to be soft and hard sealing forms, with reliable sealing. Repair port is configured on the valve body for easy repair and maintenance.