The vertical incidence reflectivity of conformai perfectly matched layer (PML) is an essential property that can demonstrate partly the error and efficiency of absorbing boundary condition (ABC). To design the high-performance conformal PML, some parametric analysis of vertical incidence reflectivity is implemented in this paper. By deducing and solving the recursion relation of reflection coefficient of multilayer conformal PML, the influence trends of basic parameters on the reflection coefficient of multilayer spherical PML are obtained. It is proved that this parametric analysis approach is reliable and valuable for creating the ideal conformal PML.