Magnetotransport properties of a single crystal Sb2Te3 topological insulator nanoflake with the thickness of 25 nm, synthesized via a vapor phase deposition method, are studied. The mobility and number of carriers are obtained through the Hall resistance measurement data. The magnetoresistance shows pronounced weak antilocalization effect. Temperature dependence of the phase coherence length confirms the 2D nature of the observed weak antilocalization effect. The fluctuations in the magnetoresistance are attributed to the combined contribution of the universal conductance fluctuation and the Shubnikov de Haas oscillations of the 2D electron gas. The Shubnikov de Haas oscillations reveal two well defined frequencies ascribed to states with spin-up and spin-down polarizations. The Rashba parameter and the energy gap between the two spin polarized subbands have been obtained and were equal to δ=0.75×10−11 eV m and ΔE=2.4 meV correspondingly.