Three-dimensional multiphysics modeling of electroporation (EP), including asymptotic electroporation (AEP), dielectric dispersion (DP), and evolution of pore radii, is proposed in this article. A boundary equivalent method is introduced to replace the membrane region with a surface boundary, which reduces the mesh generation inside the membrane and makes it possible to build a 3-D realistic irregularly shaped cell model and accurately calculate the distribution of the EP area related to the evolution of pore radii and cell surface shape. The applicable range of the equivalent boundary is discussed, and the equivalent model is verified through theoretical analysis and numerical simulation. Based on this model, the difference between the models including AEP and DP with and without the pore radii evolution submodel was investigated. A numerical analysis was performed by applying a single rectangular pulse with a duration of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\mu \text{s}$ </tex-math></inline-formula> to biological cells. The results show the significant effects of variable pore radii on the EP process. In addition, a double-shell geometry model is built to discuss the influence of pulse duration and intensity on outer and inner membrane responses related to EP and intracellular electromanipulation (IEM).