The transmission line matrix method (TLM) about the design of the shielding of the secondary equipments in power system is mainly researched in this paper. Firstly, the principles of electromagnetic shielding and the simulation of the propagation of the electromagnetic waves with TLM method are analyzed in theory and the feasibility of using TLM method to analyze the shielding effectiveness (SE) of the shielding body is researched. Secondly, TLM method is used to calculate the SE of the shielding bo...