Vias are typical discontinuities for high-speed signal transmission in printed circuit boards (PCBs). This paper proposes an equivalent multiconductor transmission-line model for via structures in multilayer PCBs. The proposed model is based on the physic-based circuit model, taking into account distributed effects. Various via structures with arbitrary via number, trace connections, and via stubs can be effectively handled in the equivalent transmission-line model, which is sufficiently accurate and fast to be integrated into circuit simulators for via and link-path analysis. With the proposed model, well-known transmission-line theories can be borrowed for via modeling and characterization for signal integrity in high-speed digital circuits. The proposed model is validated with both full-wave simulations and measurements for multilayer PCBs with different via structures.