Model-based simulation of a hydraulic closed-loop rotary transmission with automatic control of hydraulic pump and hydraulic motor is considered in the paper. The approach is based on multi-pole modelling and intelligent simulation. In the paper the functional scheme of the transmission is proposed and multi-pole models of components are introduced. Mathematical multi-pole models of components for steady state conditions and for dynamic transient responses are presented. A high-level graphical environment CoCoVila (compiler compiler for visual languages) is used as a tool for describing models and performing simulations. Object-oriented multi-pole models, visual programming environment, automatic program synthesis and distributed computing are as original approach in simulation of fluid power systems.