The work consists of six chapters, introduction, conclusions and references. The literature review, aim and tasks are described in the first chapter. The moisture and temperature caused deformations of unsymmetrical lay-up plywood sheets and rational main technological properties are analyzed experimentally and numerically in the second chapter. The third chapter is devoted to describe the created optimization method of ribbed plywood composite plate with vertical-flat ribs and to describe optimization of three span plates by the proposed method. The optimization methods of variable stiffness ribbed plates, of wood fiber orientation angle of outer layers, and optimization results of typical cases are described in fourth chapter. The analysis method and some samples of rational geometry of ribs are described in fifth chapter. The sixth chapter is used to show optimization results of typical structures, used in structural and machinery applications, and described experimental validation of the main results.