A new optimization technique of ribbed plates with discrete varying (heterogeneous) stiffness is proposed. It consists of analysis of optimal continuous varying stiffness, division of plate into discrete domains and sizing optimization of plate’s internal structure. The optimal continuous varying stiffness is obtained by minimizing structural compliance and differences of stress fields. The geometry of plate’s internal structure is optimized by using trained Feed-Forward Artificial Neural Network and Genetic Algorithm. A method to avoid of stress concentrations in connections of discrete domains is proposed.