The invention relates a nanometer SiO2- organosilicon coating and preparation method. The coating comprises the 60-82% organosilicon resin, 3-10% nanometer SiO2, 5-15% dimethylbenzene, 3-8% toluene, 3-6% butyl acetate, 0.2-0.6% dispersing agent, 0.1-0.3% levelling agent, 0.2-0.4% defoaming agent, and 3-10% talcum powder. The method comprises the following steps: 1 weighing nanometer SiO2, adding dimethylbenzene, dispersing agent and butyl acetate, disperse with ultrasonic, and getting nanometer SiO2 slurry; 2 weighing organosilicon resin, adding defoaming agent and dispersing agent, then adding nanometer SiO2 sluury and talcum powder, dispersing and grinding; 3 adding left resin, solvent and adjuvant, and dispersing. The invention can improve the erosion-resisting characteristics, protect material, and extend the life.