Abstract: The analysis of electromagnetic coupling of complex cable bundle system is becoming more difficult with the increasing complexity of the electromagnetic environment. The development of high power electromagnetic radiation technology brings serious electromagnetic threat to those which have complex cable bundle systems and electronic equipment systems. Related to the electromagnetic attacks and electromagnetic protection, there is an urgent need in the aspect of analysis of electromagnetic coupling of complex cable bundle system. Due to the complex geometrical space boundary conditions of complex cable bundle system, it is hard to solve this problem using methods such as the finite difference time domain method(FDTD) and the finite difference frequency domain method(FDFD). Based on the transmission line theory, we use the decomposition skill according to the topology structure to build up a topological model of electromagnetic coupling of complex cable bundle system, and we obtain a method to calculate the terminal voltage and current of the system. We present some simulation examples to verify the availability of electromagnetic topology method in dealing with the electromagnetic coupling effect of cable network.