This paper puts forward a development method of ship motion simulation system that can conduct UDP
communication in real time. This system is based on Simulink in order to meet the need of modular and fast ship motion
simulation systems. First, the mathematics models of ship motion are set up based on the modular ideology, which
includes thruster model and models of wind, wave and current. Then, real time simulation module using S-fun function
is developed, and built into executable program. This could realize real time communication between ship motion
simulation system and visual simulation system and induce real time communication between ship motion system and
ship simulation control system. In this way, it can save time and cost when developing the simulation system. This
method has been used successfully in the development of real time simulation system of some engineering ship.