Abstarct: In this thesis, the static and dynamic response of a clamped-clamped nanocomposite microbeam under combined electrostatic and piezoelectric actuations is analyzed. To deriving equations of motion are used the Euler-Bernoulli beam theory and Kelvin-Voigt model due to viscoelastic structure of microbeam. The nonlinear model for the system is studied by considering stretch of mid-plane, a electrostatic force, an harmonic force and the piezoelectric effect. Then the piezoelectric actuation is applied with voltage equal to between the upper and lower sides of the piezoelectric laxyer. After that the equation of motion has been derived by using the Hamilton principle, then for static deflection and natural frequency Galerkin method is used. The dynamic response of the system was obtained using the Galerkin method and the multiple scale perturbation method. In this paper, the effect of the design parameters on the static and dynamic response is discussed and a softening or hardening behavior has been obtained. Also the effect of structure damping on static and dynamic behavior is investigated.