Infrared vibration spectra of nanosize (SiO2)n,O2H4 with line, ring and cage structures were calculated using the density-functional theory (B3LYP) at 6-31G(d) level. For quasi 1D (one dimension) line and ring structure, the frequencies of stronger infrared vibration modes monotonically change as a function of the length, which shows strong size effect. The IR vibration modes in directions parallel and perpendicular to the axis of nanoline or nanoring have opposite size dependence trends, showing the real vibration anisotropy property of nano scale material. Due to constructional complexity, cage structure does not have quasi 1D character. Morever, IR vibration modes increase as structural symmetry decreases. Vibrations of two-membered ring, isolated hydroxyls of three structures and framework SiO4 tetrahedron in cage structure agree well with experimental data. Theoretical calculation result of IR spectra can be used to guide characterization of silicon oxide nano scale materials fabricated in experiment.