The invention discloses a length-adjustable ring buckle scaffold cross rod. The length-adjustable ring buckle scaffold cross rod comprises a central bidirectional threaded screw rod right-handed screwrod, a central bidirectional threaded screw rod left-handed screw rod, a central limiting sleeve, a left cross rod, a right cross rod, a length adjusting valve, cross rod limiting pieces, a right-handed thread, a left-handed thread, a left cross rod right-handed thread and a right cross rod left-handed thread. The problem that a traditional modular ring buckle scaffold cross rod cannot be normally used in a non-modular space (the distance is non-modular, and a ring buckle vertical rod cannot be arranged at the bottom of a beam through a ring buckle cross rod) is solved, and the ring buckle scaffold cross rod has the advantages of being rapid to mount, high in applicability, easy to operate, high in stability, safe, reliable and the like. Normal use of a ring buckle under the non-modular interval is well guaranteed, it can be guaranteed that an under-beam vertical rod is arranged at the middle through adjustment of the length of the ring buckle scaffold cross rod, and therefore, the under-beam vertical rod can better support an under-beam frame body, the safety of the under-beam frame body is enhanced, and simplification of reinforcement of the under-beam vertical rod is achieved.