The invention discloses a simulation design method for an AC coupling capacitor reference plane. The method comprises the steps of S1, establishing a PCB model, wherein a hole digging size of an impedance hole is gradually increased by 2mil from a size equal to that of a pad, until the lower side of a capacitor is integrally hollowed; S2, extracting a PCB S parameter through utilization of Sigrity Power SI, importing the S parameter into Hspice for TDR impedance simulation, thereby obtaining a TDR impedance simulation curve and the TDR impedance simulation curve at the position of the capacitor; S3, extracting the impedance at the position of 470ps, obtaining impedance values corresponding to 7 cases and drawing an impedance change curve; and S4, analyzing a simulation result. The method has the beneficial effects that 1, through comparison of various elliptical hole digging modes, a hole digging area with the best impedance continuity effect is found, the impedance continuity of a link is ensured, thereby achieving a signal completeness purpose; and 2, the elliptical hole digging size is researched, thereby obtaining the best hoe digging area, the method is high in operability, is easy to realize in design and production and can be widely applied to the field of high-speed PCB design.