Abstract: Surface modification with silicon coupling reagent was used to treat ultrafine silicon dioxide waste material in fiber manufacturing. Then mesoporous powder of SiO2 was synthesized by using the modified material. The experimental results with Fourier transform infrared (FTIR) spectroscopy and thermogravimetric (TG) analyzer showed that the surface Si－OH bonds infrared intensity of ultrafine silicon dioxide decreased and thermogravimetric loss increased，indicating reaction of the surface Si－OH bonds of ultrafine silicon dioxide with silicon coupling reagent. By laser light scattering (LLS) determination the particle size of ultrafine silicon dioxide decreased and the dispersibility was obviously improved，indicating enhanced hydrophobic property of ultrafine silicon dioxide after modification. The structure appearance of silicon dioxide powders was characterized with transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results showed that it was possible to synthesize ordered porous material of SiO2 at an appropriate temperature. This surface modification provides a wide market to reuse ultrafine silicon dioxide waste material.