Abstract: The cracking of BM510 steel plates for automobile frames happened in the process of cold bending.The chemical compositions,mechanical properties,optical microscopy ,SEM and EDS,continuous casting process had been analyzed.The results show that the cold bending cracking of BM510 steel plates for automobile frames were caused by the inclusions aggregated unconventionally.The measure for reducing the inclusion aggregation is to control the casting speed and avoid high fluctuation of casting speed.