The nonlinear modelling strategy and simulation of flexible components in micro-electro-mechanical structures are addressed in this paper. A newly developed Cosserat rod element approach is employed to model the dynamic equations of motion for MEMS components which are prone to nonlinear (moderately large amplitude) vibrations. Models constructed using this approach seek to capture the most significant characteristics of a microstructure in a few variables governed by a few ordinary differential equations of motion. For illustration, a resonator that comprises a resonator mass supported by four flexible beams is investigated using the proposed approach. A three-dimensional nonlinear dynamic model with six degrees of freedom is generated for the resonator. Finally, the nonlinear dynamical response of the resonator without external forces and torques has been presented through numerical simulations.