The invention relates to the field of leveling of multisection cross beams, in particular to a truss robot multisection cross beam horizontal adjusting device. An upper inclined surface is arranged at the upper part of an inclined surface fixed block; a lower inclined surface is arranged at the lower part of an inclined surface adjusting block; the upper inclined surface and the lower inclined surface are consistent in inclination; the inclined fixed block is fixed at the upper part of a truss stand column; the inclined surface adjusting block is put on the upper inclined surface of the inclined surface fixed block; the upper inclined surface of the inclined surface fixed block is contacted and mounted with the lower inclined surface of the inclined surface adjusting block; a large notch fixed stopper is fixed in a groove formed in the upper part of the truss stand column; a small notch fixed stopper is fixed on the side surface of the large notch fixed stopper; an adjusting bolt and the inclined surface adjusting block are horizontally connected through a thread; and a ring notch of the adjusting bolt is clamped in a U-shaped groove of the small notch fixed stopper. The device realizes horizontal adjustment of multisection cross beams among all truss stand columns, and has such characteristics as long service life, beautiful appearance, simple structure and low cost.