Scratch-resistance of sol-gel derived nano porous silica films were studied. The thin films were preparedwith a dip-coating method from both one-step and two-step catalyzed silica sols, and treated in a mixture gas ofammonia andwater vapour afterwards. The thin films were characterized by using Atomic Force Microscope (AFM), ellipsometer, Fourier-transform Infrared Spectroscope (FTIR), respectively. Experimental results have shown thatthe two-step catalysis remarkably improves strength of the films, and abrasion-resistance and adhesion of the silicafilms were further increased after the mixture gas treatment. It is attributed to the cross-linking of silica particlesin the sols by randomly branched or/and entangled linear chains and more Si O Si bonds formed by the mixturegas treatment.