The invention discloses a rotation lock structure used for a car seat. The car seat includes a lazyback and a cushion. The lazyback and the cushion are connected with each other through a rotation lock in a rotation mode. The rotation lock structure includes a lock pulling mechanism, a lower supporting frame plate, an upper supporting plate and a rotation lock body. The lower supporting frame plate is connected with the cushion. The upper supporting plate is connected with the lazyback, wherein, the rotation lock body includes a cover plate, a guiding plate, a pulling rod, a locking plate, a spring and a tooth plate. The rotation lock structure used for the car seat has the following advantages that (1), the rotation lock structure is only provided with twelve components; compared with a normal lock assembly structure, five parts are omitted; and in the situation that it is ensured that the strength is not changed, the weight is greatly reduced, the cost is reduced, and the rotation lock structure is in line with the current seat lightweight development trend; (2), assembly can be completed only through one riveting and four welding, and assembly is simple and convenient; and (3),a semi-closed structure is used, and the risk that foreign matters enter the mechanism resulting in unlocking is reduced.