Using higher-order shear deformation theory (HSDT), nonlinear analysis of polymeric plate under uniform transverse pressure is studied considering material nonlinearity for viscoelastic material. The multiaxial stress state of the Schapery single integral equation describes the material behavior by recursive-iterative formulation. The finite difference Dynamic Relaxation (DR) method is utilized to study the annular sector plate, including geometric nonlinearity with in-plane fixed and free clamped and hinged edge constraints. The plate is considered as a laminate of isotropic layers, in which the viscoelastic properties of each layer have their own parameters during the loading. The plate deflection is predicted for different thicknesses and also various pressures at the beginning and end of loading and compared with elastic finite element results. The normal and through-thickness shear stresses are also determined in different time steps.