Abstract: The physical processes of X-ray irradiating cable were analyzed in this paper. The calculation models of dielectric’s radiation-induced conductivity (RIC) and gap effects were built up. The two-dimensional finite-element method was employed to simulate the nonlinear effect and the nonlinear regularity of the Norton-equivalent current driver (NCD) was concluded in detail. The simulation results show that the NCD’s amplitude tends to be saturated and its pulse width tends to be narrower with the increase of X-ray fluence when the RIC effect exists only. The NCD’s amplitude is in direct proportion to the gap width when the gap effect exists only. Meanwhile, the gap effect can counteract the RIC effect greatly when both effects are considered. Therefore, nonlinear effect caused by both effects should be taken into account for the predication of cable’s responses under nuclear explosion X-ray.