  We investigate the electronic structure of tungsten ditelluride (WTe$_2$)
flakes with different thicknesses in magneto-transport studies. The
temperature-dependent resistance and magnetoresistance (MR) measurements both
confirm the breaking of carrier balance induced by thickness reduction, which
suppresses the `turn-on' behavior and large positive MR. The Shubnikov-de-Haas
oscillation studies further confirm the thickness-dependent change of
electronic structure of WTe$_2$ and reveal a possible temperature-sensitive
electronic structure change. Finally, we report the thickness-dependent
anisotropy of Fermi surface, which reveals that multi-layer WTe$_2$ is an
electronic 3D material and the anisotropy decreases as thickness decreases.
