This article reveals the essence of the phenomenon of optical illusion, its role in the design. A comparative analysis of op-art and design with the use of optical illusions has been carried out. An analysis of the compliance of design with the use of optical illusions with the principles of Gestalt psychology is presented. The dependence of readability of product design on compliance with the greatest number of gestalt laws is traced. The set of rules for design shaping using optical illusions is removed.