The invention discloses a locking device for a self-lifting type platform pile leg. The locking device structurally comprises a reinforcement rod, a round locking rod, a recess, an installing bolt, aprotrusion, a locking opening, a main body, a first transverse rod, movable rods, a second transverse rod, movable lock catches, a locking mechanism, a sliding opening, a fixing bolt and a cover plate, wherein the first transverse rod and the second transverse rod are parallel; the middles of the first transverse rod and the second transverse rod are perpendicularly and fixedly connected through the reinforcement rod; the two ends of the first transverse rod and the two ends of the second transverse rod are movably connected through the movable rods; the movable rods are movably connected withthe second transverse rod through the movable lock catches; the locking opening is formed in one side of the main body; and the square protrusion is horizontally welded to the inner wall of the locking opening. The locking device for the self-lifting type platform pile leg is provided with the movable lock catches and the locking mechanism, the locking mechanism and the round locking rod make full contact with the self-lifting type platform pile leg, four corners are balanced, a limiting mechanism is ingenious, the movable lock catches have sufficient pressure and are not prone to falling, and the effect that the self-lifting type platform pile leg does not incline under the action of wind force is guaranteed.