Abstract: A coilgun design code is programmed according to the formulas describing the inductive coupling between the thrust coils and the armature, the dynamic response of the armature, and the ohmic heating in the thrust coils and armature. The algorithms determining the operation status of the driven pulse forming network are presented. The convergence of the code is analyzed. The maximum time-step and mesh size of the armature are dependent on the rise time of the driven pulse current. The code is validated by comparing the simulated results with the experimental ones. The calculated coil current wave is in agreement with the experimental results. However, the calculated velocity is higher than the measured one about 6.5%. The convergence and validation of the code indicate that it can be used for the primary design for a coilgun system.