Abstract: To investigate the coupling mechanism between electromagnetic pulse (EMP) and transmission line network, taking two familiar networks, tree networks and annular networks as examples,the transient responses of networks to EMP were studied based on a PSPICE simulation method. Firstly, the transient response experiment result of transmission line network terminated with resistance loads, the solution of BLT equation and the result of PSPICE simulation were analyzed contrastively. And the results show better consistency. Due to the calculation complexity of BLT equation, especially with the loads of capacitances, inductances or nonlinear loads, the PSPICE simulation method is useful for the questions, an annular networks terminated with capacitance, a tree network terminated with transient voltage suppressor and a multi-core cable network. And their simulation and experiment results are consistent with each other. These results all show the validity of the PSPICE simulation method in the solution for the transient responses of transmission line network about electromagnetic pulse coupling mechanism, frequency change and nonlinear loads.