To design a non-overlap vertical electrostatic combdriver for the optical translational micromirror of an optical phase modulator, a mathematic model based on the conformal mapping was built to research the driving performance of the combdriver in detail. According to the theory of complex variable function, an analytical model was established for the electrostatic field of comb actuator by conformal mapping. Then, the electrostatic force in a certain displacement range was deduced by the analytical model for researching the movable comb finger. The results were compared with the corresponding resolution by the Finite Element Method (FEM). Finally, a non-overlap vertical combdriver was successfully fabricated by Micro Electronic Mechanic System(MEMS) process, and an optical Michelson interference system was constructed to measure the static driving charateristics of the comb driver. The result shows that the displacement of proposed non-overlap vertical electrostatic combdriver is 325 nm (phase difference 2π) with a dc driving voltage of 28 V and the offset vertical comb actuator can be actuated to 2.07 μm under a dc driving voltage of 90 V. The measured results accord excellently with the simulated results using the conformal mapping and FEM method, which proves proposed analytical model to be correct. It can provide theoretical and pratical bases for design of non-overlap vertical electrostatic combdrivers.