Objective of the current work is to represent performance analysis of microsystems in the presence of pull-in instability phenomenon. To this end, the Euler-Bernoulli beam theory, and non-linear Reynolds equation are considered, and the generalized differential quadrature method (GDQM) is employed to solve the nonlinear partial differential governing equations. A parametric study conducted, focusing on the combined effects of geometric non-linearity, Squeeze-film damping (SQFD), distributed load, inertial gap, and material properties. The results reveal that the pull-in instability of poly silicon micro-beam is strongly size-dependent. It is also demonstrated that neglecting pressure in Reynolds equation will cause smaller values in pull-in time.