The diffuse reflection spectroscopy (DRS) method was used to study the properties of strontium bismuthate Sr3Bi2O6 in a wide temperature range. It is established that after the Kubelka-Munk transformation and logarithmization, it is possible to distinguish three linear sections on the DRS. The presence of such linear regions at energies smaller than the bandgap is usually associated with electron-phonon interactions in the crystal and is described using a model based on the Urbach rule. A high-energy linear region can be associated with a direct transition of electrons from the valence band to the conduction band. The remaining linear sections can be associated with the transfer into the conduction band of electrons biographically localized in deep traps in the bandgap.