Pair deceleration machine gear of movement is through pair pair of tooth surface meshing movement to completed of, pair Le collection tooth surface of relative movement and contains scroll and sliding, for passed power of gear, to research gear of by force and deformation. need application mechanical knowledge, gear two tooth surface Zhijian has lubricants, and involved fluid mechanics of knowledge. If research run with agent and gear surface mutual role generated of surface film, need physical, and chemical aspects of knowledge. Therefore, in the lubricant condition, to true comprehensive view gearing kinematic and dynamic problems must take into account the presence of lubricants. Included lubricant for gear design, which is more comprehensive and sound design.