The basic features of complex dynamical and control systems, including systems having hierarchical structure, are considered. Special attention is paid to the problems of synthesis of dynamical models of complex systems, construction of efficient control models, and to the development of simulation techniques. An approach to the synthesis of dynamic models of complex systems that integrates expert knowledge with the process of modeling is proposed. A set-theoretic model of complex system is defined and briefly analyzed. The structure of the model is described, and architecture of computer simulation system is presented, requirements to and components of computer simulation systems are analyzed.