The utility model relates to an underwater double-unlocking connector which comprises a through pipe-shaped main body, an outer wall cylinder sleeved at the outer side of the main body, a toroidal horn body arranged at the bottom end of the outer wall cylinder, a locking ring connected with the toroidal horn body, a piston cylinder arranged between the main body and the outer wall cylinder in a sliding way and a mechanical unlocking sleeve sleeved at the upper part of the outer side of the outer wall cylinder in a sliding way. The underwater double-unlocking connector adopts the hydraulic and mechanical double-unlocking methods, can realize the accurate, high-efficiency and reliable locking and unlocking for an underwater well or a hub base and has high reliability and high operation efficiency on the sea. The underwater double-unlocking connector adopts a pinion and rack mechanical locking method, has a simple structure, is convenient to operate and is safe and reliable.