For the problems of high aspect ratio, thin wall thickness, and easy cracking during the forming process of a special nail shell, the structure and main design parameters of cupping die were studied. Then, for two types of die with straight wall and inclined wall, the load on the die as well as the deformation and damage of the cup in the punching process were compared, and an inclined wall die with lower load, smaller bottom thickness reduction and smaller tendency to damage was determined to use. Furthermore, the orthogonal simulation experiments of nail shell cupping were conducted using the inclined wall die, the influences of three main parameters, namely, punch fillet radius r, die fillet radius R and die cone angle α on the cupping were studied. The results show that the influence order of the three main parameters of the die on the bottom thickness reduction and maximum damage value is as follows: punch fillet radius r>die cone angle α> die fillet radius R. The optimal combination of structural parameters is r=2 mm，R=3 mm and α=20°.