Pull-in　parameters　analysis,　such　as　pull-in　voltage　and　pull-in　displacement,　of　contact　type　electrostatically　actuated　MEMS　switches　is　investigated.　Using　Euler-Bernoulli　beam　theory,　a　cantilever　beam　model　is　established.　Based　on　the　method　of　Galerkin　decomposition,　the　model　is　changed　to　a　discrete　modal　equations,　including　nonlinear　electrostatic　force.　Based　on　the　equilibrium　stability　analysis,　pull-in　voltage　and　pull-in　displacement　are　discussed.　The　simulation　results　can　be　used　as　design　tools　and　rules　to　improve　switch　performance.