  Tungsten ditelluride (WTe$_2$) exhibits extremely large and unsaturated
magnetoresistance (MR). Due to the large spatially extensions of Te-5p and W-5d
orbitals, the electronic properties of WTe$_2$ are sensitive to the lattice
structures, which can probably affect the strongly temperature dependent MR
found in experiment. Based on first-principle calculations, we investigate the
temperature effect on the lattice and electronic structures of WTe$_2$. Our
numerical results show that the thermal expansion coefficients of WTe$_2$ are
highly anisotropic and considerably large. However, the temperature (less than
300 K) has ignorable effect on the Fermi surface of WTe$_2$. Our theoretical
results clarify that the thermal expansion is not the main reason of the
temperature-induced rapid decrease of magnetoresistance.
