The invention provides a ceiling structure capable of being freely dismounted. The ceiling structure comprises rubber bushings, rubber broached bushings, broached grooves, limiting baffle rings, reserved threading pipes, short welded pipes, angle iron and broached holes. A keel frame body is of a rectangular frame structure which is formed by welding four rectangular pipes, and hanging pipes are also each of a rectangular frame structure which is formed by welding four rectangular welded pipes. Two hanging pipe cross struts are welded to the inner side face of a frame of each hanging pipe, andthe pipe walls of the two short edge welded pipes of the rectangular frame structure of each hanging pipe are each provided with the corresponding outward-extending short welded pipe in a welded mode. Reinforced supporting pipes are each of a rectangular pipe structure, the left end faces and the right end faces of the reinforced supporting pipes are each provided with the corresponding reservedthreading pipe which is of a circular pipe structure in a welded mode, and inner cavities of guiding sleeves are further each provided with the corresponding rubber bushing in a gluing matched mode tobe provided with structures of the corresponding reinforced supporting pipe and the corresponding hanging pipe in an inserted mode to achieve sliding adjusting, so that more convenience is achieved when the inserted reinforced supporting pipes and hanging pipes are mounted on the keel frame body.