A new optimization technique of composite plates with discrete varying stiffness is proposed. It consists of threemain steps. Analysis of optimal continuous varying bending and shear stiffness of plate is done in the first step by minimizing structural compliance and stress field differences. Size optimization of discrete domains is done in the second step by solving minimization problem with a Genetic Algorithm. Dimension optimization of plates internal structure is done by previously trained feed-forward artificial neural net work in the third step. A simply supported rectangular plate with uniformly distributed load and multi-span plate with concentrated loads are optimized by the using of proposed method. The deflection of optimized plate could be reduced up to 50%, and average increase of strength to mass ratio is about 20%.