The nonlinear dynamic equation of a laminated beam subject to parametrically deterministic excitation is derived based on the general von Karman-type equations and the Reddy third-order shear deformation plate theory. The first mode parametric resonance is taken into consideration using Galerkin approach. The modulation equations are obtained with the method of multiple scales. The frequency-amplitude and force-amplitude characters are investigated. Results show that the nonlinear behaviors belong to hardening effect.