The working principles and characteristics of electrostatic oil purifier and balanced charge agglomeration oil purifier were introduced.The application was discussed of the two purifiers in oil press,hydraulic system of shield tunneling machine,hydraulic oil unit of hydropower station,turbine system of thermal power plant and marine electronic diesel engine lubricating system,and etc.The problems were analyzed in the practical application of the two purifiers.The application result shows that the electrostatic oil purifier and balanced charge agglomeration oil purifier with high filtration precision can effectively remove the submicron particles in the oil,and strip the sludge,varnish and gels formed in the internal system with good effects.