The utility model provides an airtight butterfly valve of granary, the casing is upper and lower open structure, be provided with the valve block in the casing, the under shed of casing is fixed with down the connecting piece, the upper end of connecting piece is goed deep into inside the casing down, the upper end of valve block pressure equipment connecting piece under, be provided with sealed the pad between valve block bottom surface and the lower connecting piece top surface, the pivot is connected through initiative link mechanism to the valve block top surface, the pivot transversely runs through the casing, and the relative casing of pivot rotates, the pivot is rotated through initiative link mechanism lifting valve block, the one end that the pivot is located the casing outer is provided with the handle. The utility model relates to a from top to bottom the open -close type valve drives the pivot through the handle and rotates, and the pivot is passed through link mechanism and is driven the valve block and go up and down, realizes the airtight of valve and opens, and link mechanism's setting can the airtight precompression occasionally of effectual assurances valve, fully guarantees inclosed reliability, and the resistance is little when opening, can effectually overcome the defect that current airtight butterfly valve of granary is airtight not sternly, the resistance is big, the sealing washer easily weares and teares.