The present status and development trends of nano-composite coatings were briefly introduced. The nano-SiO_2 was dispersed into crylic acid resin by ultrasonic wave and high-energy ball milling, the influence of nano-SiO_2 on shielding property of coatings was investigated. Relation between particle size distribution of original nano-SiO_2 and its dispersal in water and alcohol after treatment were analyzed, respectively. The ultraviolet permeation rate of coatings filled with nano-SiO_2 was detected by ultraviolet spectral photometer. And the particle size distribution of coatings was examined by TEM. The results show that particle size distribution is comparative convergence and smaller one order of magnitude after dispersal treatment. The size of most nano-SiO_2 in coatings is smaller than 100nm, which indicates that the amount of nano-SiO_2 in the resin is 20% (solid content of resin), the permeation rate of ultraviolet of composite coatings decreases to 20%. The research of its excellent ultraviolet shielding property mechanism indicates minor size and high surface energy of nano-SiO_2 can produce different absorption, reflection and scatter actions to different wavelengths. The present status and development trends of nano-composite coatings were briefly introduced. The nano-SiO 2 was dispersed into crylic acid resin by ultrasonic wave and high-energy ball milling, the influence of nano-SiO 2 on shielding property of coatings was investigated. Between particle size distribution of original nano-SiO 2 and its dispersal in water and alcohol after treatment were analyzed, respectively. The ultraviolet permeation rate of coatings filled with nano-SiO 2 was detected by ultraviolet spectral photometer. And the particle size distribution of coatings was examined by TEM. The results show that particle size distribution is the comparative convergence and smaller one order of magnitude after dispersal treatment. The size of most nano-SiO 2 in coatings is smaller than 100 nm, which indicates that the amount of nano-SiO 2 in the resin is 20% (solid content of resin), the permeation rate of ultraviolet of composite coatings reduces to 20%. The research of its excellent ultraviolet shielding property mechanism indicates minor size and high surface energy of nano-SiO_2 can produce different absorption, reflection and scatter actions to other wavelengths.