Keywords: In this paper, based on the method of blocked zones, we consider a practical method for synthesizing a single-crank-and-rocker mechanism based on a given coefficient of change of an average speed of the slider and the optimal transmission angle to ensure the maximum transfer of force from the input link to the working body (output link). Based on the above method, we developed a dialog design system on PC, made in the visual system Delphi 7, which allows you to determine the parameters of the synthesized four-link hinge mechanism by the optimal pressure angle and conduct kinematic analysis of the movement of the links in the dialog mode.The software package is considered as a tool for designer when designing machines using the four-link mechanism.