The invention discloses a method for improving oil resistance of a rubber member. The method includes: coating the surface of a rubber sealing member with a layer of specially-prepared size; putting the rubber sealing member into environment at temperature of 95-100 DEG C for drying and curing for 1-2h, wherein the size is prepared from modified molybdenum disulphide, sodium pyrophosphate, urea resin, silane coupling agent, antiager and ethyl acetate. The rubber member treated by the method has high wear resistance and oil resistance, high comprehensive using quality, long service life and high market competitiveness.