The transmission spectra and optical absorption edges (OAEs) of some scheelite structured crystals, such as undoped CaWO 4, PbWO 4, CaMoO 4 and PbMoO 4 crystals, were comparatively studied. It was found that the relative location of their OAEs can not be explained from a widely adopted viewpoint that the OAEs originate from electron transfer from t 1 orbital to 2e orbital of W(Mo)O 2- 4 group with T d symmetry. But it can be explained with the electron transfer from 1a 2 orbital to 2b 1 orbital within the W(Mo)O 2- 4 group with D 2d symmetry. The OAEs of the above mentioned crystals and the PbWO 4 crystals doped with lanthanum, niobium and molybdenum respectively were interpreted briefly from the present viewpoint and the ion polarization model.