Friction can lead to dead zone and hysteresis in steady state and dynamic characteristics of a servo proportional system.Machinery lubrication can reduce the maximum static friction force between servo spool body and chamber,thereby enhance the system response characteristics and improve the control accuracy.The concept of machinery lubrication was introduced and its mechanism was analyzed in detail.A dither circuit of machinery lubrication and the method of its adjustment were introduced to conduct a couple of experiments,whose results verify its application effect in servo proportional system.