Pantograph frame multiple rigid-body dynamics model with R/W equation based on relative coordinate system was built,and the motion differential equations and constraint equations were derived. Based on Lagrangian Multiplier Method and constraintviolation stabilization method, the motion differential equations were resolved. Numerical simulation of pantograph static (with gravityaction) and dynamic (with simple sinusoidal interference) state was carried out, and the rotation angle and torque result was comparedwith multiple dynamics software Recurdyn. The max error 1.14% of the comparing results validated the accuracy of the built model.