An electrical-capacitance-tomography sensor consists of a set of measurement electrodes. It is difficult to calculate the capacitance for a given sensor structure and given permittivity distribution, which is called solving the forward problem, theoretically. Therefore, finite-element methods (FEM) and finite-difference methods are commonly used to solve the forward problem and to generate a sensitivity matrix for image reconstruction. This paper presents a new approach to solving the forward problem based on a capacitor-mesh model. It has been used for iterative image reconstruction using an updated sensitivity matrix according to an estimated image. In this paper, some simulation results are presented and compared with the results obtained using an FEM software package from Ansoft Company, showing that the new approach is promising.