The effect of treatment with γ-aminopropyltriethoxy silane (γ-APS) on the corrosion resistance of zinc-silica composite which was electroplated onto mild steel substrate has been studied by salt spray testing, measurement of spontaneous electrode potential in concert with contact angle to water, and FT-IR spectroscopy. Composite surface roughness was regulated with the aid of surfactants in the bath. The red rusting time of non γ-APS treated composite containing 3.6wt% of 0.018μm silica particles was found to be 1200hr, which corresponds to about twelve times the salt spray resistance of the pure and fan-shaped zinc electroplate of the same mean thickness. A red rusting time of 2800hr was recorded when the same sample was treated with γ-APS solution. Spontaneous electrode potential measurement of the nontreated composite showed that a protective film is formed on the composite surface in 5% NaCl solution. The excellent red rusting resistance of the treated composite is ascribed to formation of a chemically fixed hydrophobic layer on the composite surface.