Abstract: Transparent nano TiO₂-ZrO₂/Poly(MMA-co-MSMA) organic-inorganic composite was prepared by an in situ sol-gel process with methyl methacrylate (MMA) and 3-(trimethoxysilyl) propyl methacrylate (MSMA) as couplingagents. Titanium isopropoxide and zirconium n-tetrabutanoxide were used for the synthesis of the titania-zirconia network. The composite was characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet spect rophotometer (UV), Spectro-Ellipsometer, scanning electron microscope (SEM) and thermo-gravimetric analysis (TGA). With the increase of the TiO₂-ZrO₂ inorganic content, the refractive indices also promote and ultraviolet absorption becomes stronger. At the same time, the nanoparticles size increases from 20～30 nm to 80～ 90 nm and the composite still keeps transparency. Nanocomposite heat resistance shows conspicuous improvement. The highest carbon yield at 800 ℃ improves with the increase of the inorganic content and the best result is 71 %.