Based on convolutiontype constitutive equations for linear viscoelastic materials with damage and von Kármán’s hypotheses, the equations governing quasistatic behavior of thin plates with damage were derived under large deformation. It can be seen that the derived equations are a set of nonlinear integro partialdifferential equations. In order to analyze the equations, the Galerkin method was firstly applied to simplify the set of equations into a set of integral equations.