This paper presents numerical simulation results for a novel constant-charge (CC) biasing method for automatically controlling the voltage across the dielectric of the capacitive RF MEMS switch. An electromechan ical 1-D nonlinear model that takes into account variable damping of the medium (e.g., air) and contact forces of the surface of the dielectric was used for numerical simulations. Numerical simulation results for the CC biasing method are compared with those of the constant-voltage (CV) biasing method for doubly-clamped capacitive RF MEMS switch. It was found that the higher initial voltage of the CC biasing scheme results in faster switching times while the maximum electric field across the dielectric with CC biasing is significantly less than CV biasing. Such a reduced electric field of CC biasing is considerably less prone to dielectric charging resulting in a significant improvement in reliability.