A free impacting sheet forming experiment was designed to examine the influence of charging energy and frequency on the acceleration and impacting velocity caused by the Lorentz Force. The skin effect under the same frequency with workpieces of different thickness was also studied to clarify the influence of frequency. The ratio of thickness-to-skin depth varied from 0.78 to 1.17. In this study, a high-speed camera was used to record the free flying process, from which the retrieved images were used to characterize the forming velocity. Additionally, the electromagnetic module of Ls-Dyna software performed a fully coupled mechanical and electromagnetic simulation. The deviation between the simulation and the experiment was less than 10%. According to the simulation and experimental results, the frequency seems to have a more significant effect than the skin depth on electromagnetic forming. When the frequency is higher, the variation in acceleration fits the duration time of the first pulse of current. Additionally, in the frequency range between 4 kHz and 11.3 kHz, the skin effect is not a critical parameter and can be neglected.