Abstract: Numerical simulation method is an effective tool to calculate cathodic protection (CP) potential in practice. The currently used boundary conditions for this tool can be divided into two types: distribution model and time-dependent model. Boundary condition type and the corresponding processing method will have direct influences on results. Three type boundary conditions for CP simulation are reviewed: the first boundary condition or Dirichlet condition (with a known CP potential distribution), the second boundary condition or Neumann condition (with a known current density distribution) and the third boundary condition (with a known function relating CP potential and CP current density). The determination method for anodic and cathodic conditions and the processing method for nonlinear boundary condition are also discussed in detail. Results show that piecewise linear fitting is better than the Newton-Raphson fitting in flexibility and practicability, especially for polarization curve processing coming from lab measurement. More attention should be paid to the study of CP polarization model for a better CP boundary condition.