In order to solve the problems of insufficient forging and folding in the multi-station hot die forging test of a automobile deep-hole part and make up the process defects, the forging process of each station for the deep-hole part was simulated and analyzed sequentially by software Deform-3D, and by comparing with the die forging test, it is found that the defects produced in the simulation are consistent with those in the test and the occuring time nodes are the same, which proves the reliability of the simulation model. Secondly, according to the cause of defects, the part shape of preforming station is changed to optimize the material flow during the pre-forging effectively, and avoid the folding defects. At the same time, the flash groove structure of final forging die is improved, and the flow limiting ability is improved by using the resistance wall, which effectively prevents the occurrence of insufficient forging defects in the final forging process. Finally, the improved process was tested by hot die forging test, and the results show that the simulation process is accurate, there are no insufficient forging and folding defects in the deep-hole parts, which solves the actual problem. Meanwhile, the deep-hole parts are fully formed, and the shape and size meet the requirements of product processing technology.