In order to analyze the causes of wing surface cracking in the forming process of the longitudinal beam of hot rolled high strength automobile beam steel, the cracks at the cracking position were analyzed by means of macroscopic observation, scanning electron microscopy (SEM), metallographic analysis and macroscopic examination. The results showed that the main reason for the cracking of longitudinal beam wing surface was the poor surface machining quality at the end of the wing surface. There were scratches and microcracks. When the end of the wing surface was subjected to additional tensile stress in the process of continuous roller forming, the crack propagation was generated, which led to the cracking of the longitudinal beam wing surface. In view of such cracking, it was suggested to take measures to improve the processing and shearing quality of hot rolled sheet, so as to avoid the cracking caused by shearing quality effectively.