The motion of a pair of gear reducer is accomplished by a pair of pairs of tooth surface meshing motion. The relative motion of a pair of LAK tooth surface includes rolling and sliding. For gear transmission, it is necessary to study the force and deformation of the gear. It is necessary to apply the knowledge of mechanics, the lubricating oil between the two gear surfaces of the gear, and the fluid mechanics. Knowledge. If we study the surface film generated by the interaction between the lubricant and the gear surface, we need physical and chemical knowledge. Therefore, under the condition of lubricants, the existence of lubricants must be considered in order to reflect the kinematics and dynamics of gear transmission in a real and comprehensive way. The gear design of people lubricants is a more comprehensive and perfect gear design.