A quadruped robot has been considered as a vehicle having large stability margin among walking robots and pantograph leg permits large stride while providing mutual independency between vertical and horizontal movements. A quadruped robot with pantograph legs, however, has complicated kinematic characteristics to be analyzed. In order to figure. out the kinematic characteristics of three dimensional legged motions of the walking robot, we present a modeling method for three different quadruped robots with pantograph legs, which have different joint driving mechanisms. And the kinematics, inverse kinematics and geomemcal description of constraints in pantograph mechanisms are considered for animation. Particularly, motions of legs for rotation and side walking are considered in graphic simulation. Multiple windows are used to achieve efficient man-machine communication. It is showed that the software environment can be used for the simulation of various algorithms related to walking robots.