In this article the modeling aspects of an electro-static microactuator with squeezed thin film damping effects are presented. The actuator is composed of a microcapacitor whose one plate is clamped on the ground while the other plate is floating on the air with the aid of an external supporting spring. Its highly nonlinear dynamic model is linearized at various operating points. Variations of the gap between the plates and the air pressure of the system are examined in order to find possible changes in the bifurcation points or other characteristics of the system. Significant conclusions for the case of the bifurcation point have been drawn and simulation studies substantiate the presented results.