Automobile floor cross beam mounting structure and mounting method

The invention discloses an automobile floor cross beam mounting structure which comprises a floor cross beam and cross beam end plates, the cross beam end plates are arranged at the two ends of the floor cross beam, and the cross beam end plates are used for being welded to an automobile body longitudinal beam; the structures of the beam end plates at the left end and the right end are the same. The structures of the left end and the right end of the floor beam are symmetrical. Mounting holes are formed in the floor cross beams, marks are arranged on the mounting holes, the mounting holes with different marks are matched with different mounting positions, and corresponding mounting parts are arranged on the mark mounting holes matched with the mounting positions. A unification mode is adopted on a floor cross beam structure, and a universal cross beam end plate structure with the same consistency is arranged and used for being connected with a longitudinal beam of a vehicle body. The technical problem that in