Abstract: The kernal problem of control system simulation is the simultaneous solution of a set of differential and algebraic equations. There exist quite a few methods for the numerical solution of differential equations. Among them the Gear's algorithm with variable order and variable step-length is most suitable for control sys- tem simulation. The authors have developed a general-purpose intelligent simulation software which is based on the Gear's algorithm and is oriented to block diagram of typical elements and transfer function matrices. The software is highly effective, convenient and user-friendly. It is a useful tool for the intelligent design of control systems.