In view of the shortage of medical equipment road transportation simulation platform, we put forward a road transportation simulation method based on 6-DOF parallel robots. A 3D road spectrum model was built by the improvement of the harmonic superposition method. The simulation model was then compared with the standard model to verify its performance. Taking the road spectrum as the excitation, we could get the robot motion data to control the parallel robot through the S-shaped linear interpolation of the absolute position. It can simulate the movement of vehicles with different speed under various road conditions efficiently and accurately.