The invention discloses a valve flange machining production line. The valve flange machining production line comprises a machining table, a plurality of clamping parts, a driving mechanism, N first toothed racks and N+1 drilling parts, wherein N is a positive integer; a sliding groove is formed in the machining table; the sliding groove is horizontally distributed; a plurality of supporting parts are distributed in sequence in the length direction of the sliding groove; each of the supporting parts comprises a sliding block, a first supporting plate, a clamping mechanism and a first gear; each of the sliding blocks is in sliding connection with the sliding groove; each of the first supporting plates is rotatably connected with the corresponding sliding block; each of the clamping mechanisms is connected with the corresponding first supporting plate; the clamping mechanisms are used for clamping a valve; each of the first gears is mounted on the corresponding first supporting plate; the driving mechanism is used for driving the sliding blocks to move; the N first toothed racks and the N+1 drilling parts are distributed at intervals; the first toothed racks are positioned in first moving paths of the first gears; when the first gears move along the first moving paths to be in contact with the first toothed racks, the first toothed racks drive the first gears to rotate; and the drilling parts are used for carrying out drilling operation on the flange.