Flame retardant cotton fabrics were prepared based on 3-Aminopropyl triethoxysilane APTES and sodium phytate through layer-by-layer assembly. The coated cotton fabrics owned better flame retardancy. The deposition of APTES and sodium phytate and cellulose formed char residues on the surface of coated cotton fabrics during the burning process. The deposition of APTES and sodium phytate reduced the release of inflammable gases, and increased the release of nonflammable gases.