A lock structure includes a mounting plate, a positioning member, an escutcheon and a constraining member, wherein the mounting plate comprises a ring wall, guiding slot and a limiting slot, and the escutcheon comprises a limiting protrusion. The positioning member is disposed in the limiting slot and clamped between the escutcheon and the constraining member. The limiting protrusion penetrates the guiding slot of the escutcheon and is constrained inside the limiting slot. The limiting protrusion of the escutcheon is blockable by the constraining member to prevent the rotating escutcheon from separation from the mounting plate.