The blanking process and die structure of front door inner panel for a certain car model were analyzed, and it proposed to change the original uncoiled blanking production method to a fixed-length blanking method, which realized that the final blank was obtained after two blanking of the fixed-length material by adding positioning and trimming edges, and the automated production of die was debugged and matched to ensure that the blanking die could meet the requirement of mass production. Furthermore, in order to ensure the dimensional accuracy of blanking, the foam board was made at a ratio of 1∶1 according to the blanking layout diagram, which was used to compare with the sheet metal during the debugging stage to determine whether the blanking status met the subsequent production. After the automated debugging was completed, three batches of mass production were tracked to verify the stability of the blanking die, and the subsequent three batches of stamping production were also tracked to verify the stability of the blank after blanking. The production results show that the blank after fixed-length blanking has a stable forming state and the product quality meets the requirements. The blanking die after process modification has a stable automatic production state. The modification saves the cost of making a new set of blanking die and reduces the production cost, which provides idea and reference for the implementation of cost reduction production to the same industry.