The utility model provides a cross beam structure of an automobile roof, which comprises a cross beam body. The key is that the cross section of the cross beam body is M-shaped, the cross beam body is provided with a transverse penetrating stiffener, and the stiffener is provided with a plurality of stepped opening outward gluing grooves. The structure optimizes the section form of the roof beam, and transfers the stress position of the roof beam from the flange surface of the roof beam to the through stiffener, so as to ensure stronger bearing capacity of the beam. At the same time, under the condition of ensuring the same bearing capacity, the section size of M-shaped roof beam can be reduced and the material thickness can be thinned to achieve the purpose of lightweight; The gluing groove is optimized into a stepped and semi open gluing groove structure, which solves the appearance quality problems such as top cover deformation in actual production, and can meet the requirements of higher strength roof compression and collision and the needs of actual production.
