Single crystalline anatase TiO2 tetragonal nanosheet-array film on a transparent conductive fluorine-doped tin oxide (FTO) substrate was successfully prepared by hydrothermal method. The products were characterized with XRD, SEM, and transmission electron microscopy measurements. The formation mechanism of the tetragonal (001) TiO2 nanosheets is discussed and the effect of growth parameters, such as acidity, growth time, growth temperature, initial reactant concentration, and additives, are investigated. This work demonstrates a clean and effective route to the morphology-controlled preparation of large area single-crystalline TiO2 nanostructured array films on FTO glass.