Abstract: This paper presents an efficient modeling technique for analyzing the characteristic impedance of high-speed circuit based on the integral equation method.The method is presented in consideration of the specific power/ground(PG) plane structure, and is able to accurately model the 3-D electromagnetic field problem in the substrate by using a 2-D model, which significantly decreases the computing time.The proposed method does not require to obtain the specific Green function of the power/ground planes, therefore it can be applied for arbitrarily shaping PG planes.The paper also presents the simulated results of the PG planes impedance with the effects of dielectric material property ε_r, and lossy tanδ as well as the geometric factor.The results can be applied in high-speed circuit design.