In this article, dihydroxy polydimethylsiloxane (n = 5–10) was introduced into the structure of polyphosphate (PPE) to get siloxane-modified polyphosphate (SiPPE). Five kinds of SiPPEs with different Si contents were obtained. FTIR (Fourier Transform Infrared spectroscopy) ICP (Inductively Coupled Plasma Emission Spectroscopy), ³¹P NMR (Nuclear Magnetic Resonance Spectroscopy) and TGA (Thermogravimetric Analysis) were used to characterize the composition and structure of PPE and SiPPEs. Six kinds of transparent fire-resistive coatings were prepared by the mixing of amino resin with PPE and five kinds of SiPPEs. The results of the fire protection test showed that both the fire-resistive time of coatings and intumescent factor of char layers increased with the increase in content of Si. The results of TGA demonstrated that the carbonaceous residue of coating also increased regularly. The hardness, flexibility, digital photos, SEM (Scanning Electronic Microscopy) and other testing results showed that the introduction of silicon oxygen segment can effectively improve the crack resistance. The charcoal layer structure was more solid than before and collapse was not obvious after long time flame shock. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42423.