The utility model discloses a ball valve overhauls sealed mechanical locking structure, including locking screw rod (1) of upper end outband screw, the cooperation is installed the locking and is thrown and move back nut (2) on the external screw thread of locking screw rod (1), and locking screw rod (1) lower extreme is equipped with sleeve (10), and sleeve (10) upper end is fixed with the cladding in out -of -the -way cap (14) in sleeve (10) the outside, and the locking is thrown and is moved back nut (2) lower extreme and be equipped with the bulge loop, and the bulge loop lies in the locking to be thrown and move back nut (2) inboard, and the locking is thrown and is moved back nut (2) and go up the end section and be regular polygon. The utility model has the advantages of the structure is retrencied, convenient operation, be difficult for appearing the maloperation.