We study the single atom points defects in the 1T’ phase of tungsten ditelluride (WTe2) using density functional theory calculations. Various defects including vacancy, antisite, and interstitial are considered. All the considered defects are non-magnetic. Some of the generated localized defect states lie near the Fermi level, which in principle may influence the electronic transport properties of WTe2. The formation energies and the scanning tunneling microscopy (STM) images are calculated based on the obtained electronic structures. We find that, the interstitial defects have the lowest formation energy, while antisite defects have the largest. Different kinds of defects can in principle be distinguished from their corresponding STM images. These results may be helpful in the study of point defects in WTe2 using STM.