Abstract: A trailer lock down device includes a base secured to a ground insertion anchor adapted for encapsulation in a concrete block. A hydraulic jack on the base mounts a shaft for selective vertical extension and retraction. A threaded extension member is telescopically received in coaxial relation in a free upper end of the shaft and has an upper end secured to a first L-shaped member. A second L-shaped member is secured by a hinge to the first L-shaped member and is movable to a closed position to form an open ended box. A key actuated locking mechanism secures the second L-shaped member in a closed position to lock a trailer in a selected location.