In this study, transparent hybrid materials were prepared by combination of alumina fillers with different length, 15 nm (diameter) × 80 nm (length) and 4 nm (diameter) × 1400 nm (length), and acrylic surface modifiers having different numbers of acryl group. Alumina fillers used in this study could modify with acrylic surface modifier containing carboxyl groups by electrostatic interaction. The hybrid films obtained with organically modified alumina showed highly transmittance around 90％T, and TEM measurements clarified that alumina fillers dispersed homogeneously in hybrid film. As for hybrid films prepared short length alumina filler, the CTEs were decreased to around 10 ppm/K without reducing of their transparency. Furthermore, it was found that the usage of long length alumina filler allowed further reduction of CTE at lower alumina content, and improved mechanical properties and flexibility of resulting hybrid films on account of increasing of adhesion surface area between alumina and organic component.