The invention discloses a measuring device and a measuring method for concentricity of a tubular structure, and belongs to the field of measuring devices and methods. The measuring device comprises ananti-deformation tool and a measuring tool. The anti-deformation tool comprises an outer fixing ring and a plurality of connection rods. The outer diameter of the outer fixing ring is matched with the inner diameter of the first end of the tubular structure. An outer ring of the outer fixing ring is fixed to the inner wall of the first end of the tubular structure. The connection rods are arranged along the diameter direction of the outer fixing ring evenly, and are fixed to the outer fixing ring. The measuring tool comprises a support frame, a support plate, a bottom sliding rail, a bottom sliding block, a top sliding rail and a top sliding block. One end of the support frame is arranged on the top surface of the anti-deformation tool. A first through hole is formed in the anti-deformation tool. The measuring device has the advantages that the measuring tool is arranged on the top surface of the anti-deformation tool, the anti-deformation tool can provide support force to the measuring tool, and accordingly, accuracy of measurement results is guaranteed.