Abstract: In a general-purpose robot simulation system, it is important to build a model describing the robotworld accurately and showing the robot motional features effectively. Based on a motion-oriented robotgraphic simulation system, this paper covers some problems which must be considered in modelling, givesmethods to solve them, and also introduces approaches to design and implement user-friendly man-machine interface by support of SUN Workstation System. It is proved that modelling in the system is conve-nient and afficacious.