With the development of grid interconnections, the propagation phenomena of disturbance are more and more apparent. They take the form of electromechanical waves. These waves could contribute to cascading events and even large blackouts. To avoid this problem and to devise a prevention control strategy, the authors present further analysis of disturbance propagation. In this study, the disturbance propagation characteristic is studied to illuminate the influence of the network structure and the line reactance. The relationship function between generator inertia and impedance is derived. The model approach of power networks based on unsymmetrical inertia distribution is presented; the electromechanical wave model of power systems is built based on the network frame structure. The simulations are carried out to demonstrate the accuracy and effectiveness of the proposed disturbance propagation model.