6-DOF motion system capabilities on the field of simulation are becoming increasingly common. Regardless of the variety of kinematic configurations and structures, a kinematic model of the motion system has to be developed in order to determine the translational and rotational joint movements required to achieve a specified position and orientation of the missile relative to the point simulated. A generic and unified model is developed in this study as a viable alternative to the particular solutions that are only applicable to individual system configurations. Based on multi-body kinematics, each axis of the 6-DOF motion system is modeled using homogeneous coordinate transformation and small angle approximation. By synthesizing the system's parametric errors, an approach to model the effects of the positioning errors of a system's axes on the accuracy of the missile in its work space is developed. The developed versatile model makes the 6-DOF motion system model manageable and understandable.