In order to solve the weaker precision problem when using existing method to calculate some complicated shaping curve, the study was conducted. The shaping curve solution was described as initial value problems of differential equation by improving the previous geometric model and analyzing the relationships between various factors of shaping. Using mathematical programming software, the shaping curve of inside right-angle step was presented. According to the results, the three-dimensional models were established. The shaping process was simulated by the method of FEM. The rolling experiments with same parameters were conducted too. According to comparison between results of simulations and experiments, the step-face plainness and the step-slot width obtained by the new methods are better than the older, which prove this method is not only tenable, but also can get better inside right-angle step.