General kinematics simulation is only for regular mechanism about turning in fix axis, shifting on plane as well as their compound motions. However, there is no mature technique supporting kinematic simulation for those mechanisms depending on clearance operation such as lorry couplers. Considering such irregularly mechanism, authors proposed a method based on collision kinematics simulation, and combining structure analysis as well as virtual assembly in Pro/Engineer. According to methods above, authors implemented three postures of coupler operation kinematics simulation, as well as the reliability avaluation for anti-creep of coupler function. This method supplies a practical solution for irregular machine kinematics simulation.