In this paper, the Ti-O-Compound nanobelts from commercial TiO2 (annatase phase) were synthesized via the alkali-hydrothermal process. The as-synthesized nanobelts are sodium titanate, hydrogen titanate and anatase with general formula Na2Ti3O7, H2Ti3O7 and TiO2, respectively. The nanobelts are characterized by Thermogravimetric/Differential Thermal Analysis (TG/DTA), X-ray Diffraction (XRD), Infrared Spectra (IR) and Scanning Electron Microscope (SEM) apparatuses. The characterization indicates that the nanobelts with typical widths of 50 to 200 nm, thicknesses of 20 to 50 nm, and up to a few millimeters in length. The conversion mechanisms between the layer titanate and anatase of nanobelts have been discussed in this study.