Abstract
In our work we consider the issues of complex automated systems designing at the stage of engineering design. There is formulated the issue of system decomposition into applied tasks clusters subject to automation and of initial documents used for automated systems functional tasks solving. The problem is solved as a block-symmetric task of discrete programming. Solving the formulated tasks is proved to be effective with interactive algorithm which allows solving the high dimension tasks. The developed decomposition method allows optimizing the automated systems designing.