For the problem of flanging cracking for a certain automotive part of DP980 ultra-high strength steel after a period of normal stamping production, the normal production was achieved again by grinding the blanking die edge, and the influences of blanking section quality on outer edge flanging cracking were researched. Then, through comparative tests on shape accuracy, cross-sectional profile and cross-sectional morphology, it was found that the section quality of blanking parts with flanging cracking was worse than that of blanking parts with normal flanging, indicating that the poor quality of the blanking section was the direct cause of flanging cracking. Furthermore, the banking samples of the cracked batch were polished by using the grinder, and the stamping tests were conducted. There is no longer a problem of flanging cracking, proving that improving the quality of blanking section solves the problem of flanging cracking. Thus, the research has certain practical guidance significance for the stamping factories of automotive ultra-high strength steel parts.