Abstarct: In this thesis, an analytical method for dynamic-transient and steady-state modeling of variable capacitance synchronous electrostatic machines (VCSEM) for both radial field and axial field structures is presented. For this purpose, a method baxsed on calculating the capacitance matrix through obtaining the electro motive force distribution at the distance between stator and rotor and achieving the equivalent induced charge on the stator and rotor electrodes is described. Then, by obtaining differential equations of the system and using conventional methods for modeling the synchronous machines, the dynamic model of the VCSEM with the electrical equivalent circuits are achieved.The accuracy of the proposed analytical model is well verified by performing hybrid simulations and the practical experiments on the manufactured prototype. For this purpose, a three-phase multi-stack axial field VCSEM with the aim of increasing the number of poles and the possibility of increasing the power/torque is introduced, and the optimal structure is obtained for the machine using numerical optimization algorithms. The process of simulations is accomplished through finite element metode (FEM). A prototype is designed and manufactured using PCB technology and some tests are performed on the manufactured VCSEM. The results indicate that there are attractive dualities in the electrostatic and electromagnetic machines. These dualities are clearly visible on the equivalent circuits. The results show that the electrical response of electrostatic machines is fast and due to the low electric current, their electrical efficiency is very high and the mechanical loss is the major loss of these machines.