The invention discloses an automobile luggage rack sectional material and a preparation process thereof. The automobile luggage rack sectional material comprises a mounting side plate, wherein a reinforcing plate is fixedly inlaid inside the mounting side plate, a transverse rod is fixedly welded to the lower end of the rear side surface of the reinforcing plate, and a threaded hole is formed in the rear side surface of the transverse rod; the outer surface of the transverse rod is fixedly connected with a supporting plate through a through hole, the inner side surface of the through hole is slidably connected with a reinforcing rod, the front end surface of the reinforcing rod is in threaded connection with the inner side surface of the threaded hole through a threaded head, a hexagonal groove is formed in the rear end surface of the reinforcing rod, the front end of the upper surface of the supporting plate can be fixedly adhered to the rear side surface of the mounting side plate through a triangular injection molding strip, the front side of the lower surface of the supporting plate is fixedly adhered to the lower surface of the mounting side plate through a square injection molding strip, and the lower surface of the supporting plate is fixedly connected with a right-angled bracket, so that the adaptability and the stability can be greatly improved, and the efficient convenience of production and machining is ensured.