Highly dispersed silica (SiO₂) sol was prepared in a basic catalyst system using tetraethoxysilane, ethanol, and ammonium hydroxide as the precursor, solvent, and catalyst, respectively. SiO₂ antireflective films with fourth harmonic generation antireflection at 266 nm were prepared by dip coating each film in different concentrations of SiO₂ sol, and the properties of the as-prepared film were determined. Results show that the fabricated film pulled up at a speed of 4.5 cm·min ^-1 from the highest concentration SiO₂ sol exhibited the best performance. The film was characterized by a maximum transmittance of 99.307% at 266 nm, surface roughness of 1.339 nm, and excellent stability.