This master thesis deals with analysis and optimization of step fine screen mechanism. At the beginning is this thesis focused on the overview of the types of fine mechanical purification of waste water, together with an overview of commercially available solutions. The core of the thesis is analysis of the mechanism in an environment MSC.ADAMS program, with focus on the conduct of forces in the mechanism. Furthermore, optimization of the mechanism will be made of parts mechanism in an environment of ANSYS. The resulting optimized parts are processed in an environment of Creo Parametric together with drawing documentation. Optimized parts will be used in practice on step fine screens.