Bi2Te3 nanostructures were synthesized through a facie hydrothermal method. A comprehensive and systematic investigations on the effect of pH, on the purity, crystallinity, size and morphology of synthesized nanostructures were carried out. Bi2Te3 nanoparticles, nanoplates, nanoflowers and nanotubes were obtained at different pH ranges. Based on the XRD, FESEM, EDAX and HRTEM observations, a detailed growth mechanism is proposed, which shed light on the formation of primary Bi2Te3 nanoplates and the hierarchical nanostructures. Oswald ripening process is identified as the dominant growth mechanism at lower pH values. Under alkaline environment, an imperfect oriented attachment mechanism leads to evolution of nanostructures with diverse morphology from primary Bi2Te3 nanoplates. The three-dimensional nanostructures offer themselves as good thermoelectric materials due to their reduced thermal conductivity owing to the phonon scattering centres. In addition, the quantum confinement effect and the morphological fluctuation in the obtained nanostructures may improve the thermoelectric performance by resulting modified energy band structure.