Abstract: The basic equations with a generalized force field of linear elastic damage material are derived based on the theory of microstructure elasticity. The plates’ equilibrium equations and the damage control equations are provided via the utilization of theory of a small deflection plate. Under the satisfaction of displacements and damage geometrical and natural boundary conditions, the functions for computing deflection and damage are developed. At last, Galerkin method is used to calculate the buckling load of a simple supported thin rectangular plate under uniaxial compression and pure shear status.