Research on the interference influence of Intentional EMI (IEMI) in an electrical network is important to assure its working reliability. In this paper, a propagation model of disturbances in an electrical network, which consists of both galvanically connected systems and wireless systems, is established based on the Transmission Line Theory and the Baum-Liu-Tesche (BLT) equation approach. The propagation model is a straight forward analytical approach and is applied on a certain network, and the responses (voltages and electrical fields) are obtained for each load (galvanic or wireless) located in the network. The response proportions for galvanic and wireless parts are presented.