Abstract: The paper proposes an extraction method for equivalent circuits of via on printed circuit board（PCB)by using vector fitting method.The scatter parameter or admittance parameter is fitted by rational functions， then the equivalent circuits corresponding to the rational function are built.These equivalent circuits contain the physical information of the PCB via， and the speed of the signal integrity simulation can be improved.Both the single via and the differential pair of vias have been modeled as equivalent circuits，which provides an efficient approach for solving signal integrity simulation problem including PCB via.The validity of the proposed method is verified by comparing the simulation results with that of Ansoft HFSS software.