High-voltage (HV) terminations are commonly used in HV connections, such as cable-to-transformer connections, to limit local electric field intensifications that may result in electrical breakdown. The termination contains a conductor and multiple dielectric layers with an embedded semiconductive (SC) layer, which is essential for reliable insulation design and breakdown prevention. The traditional charge simulation method (CSM) for electric field calculation is limited to two pure dielectric media. The present paper is aimed at proposing a new formulation of the traditional CSM for calculation of the electric field in HV terminations with more than two dielectric layers, including an SC layer. The conductor, dielectric interfaces, and surrounding air are modeled using sets of fictitious ring charges. By considering the governing pertinent boundary conditions, namely the Dirichlet condition on the conductor surface, and the continuity of both the electric potential and the normal electric flux density at the dielectric interfaces, the simulation charges are evaluated, and hence the electric field. To account for the presence of SC layers with relatively high conductivity, a hybrid numerical approach combining the CSM and the finite difference method (FDM) is developed, where the SC region is solved using FDM and coupled to the CSM domain through the continuity conditions of potential and normal flux density. The proposed formulation is validated through comparison with COMSOL Multiphysics simulations. The results demonstrate excellent agreement in the potential and electric field distributions across all dielectric layers, including in regions near to the interfaces and sheds. The newly-formulated CSM with hybrid CSM–FDM provides an efficient and accurate tool for electric field calculation in complex plasma reactors and HV cable terminations, accommodating multi-dielectric layers, including SC ones