The effect of fast annealing treatment on the electrical properties and interface structures of Au/Hg3In2Te6 contact has been studied by means of current-voltage test and high-resolution transmission electron microscopy. The current-voltage characteristics of Au/Hg3In2Te6 indicate an improvement of the Schottky barrier height (SBH) from 0.557 to 0.601 eV after proper annealing treatment. Meanwhile, the orthorhombic AuTe2 particles with irregular morphology formed near the interface region after 200 A degrees C annealing treatment. These particles were generated by chemical reaction between Au and Te atoms rather than the phase transformation process. Two types of crystallographic orientation relationship were confirmed between AuTe2 particles and the Hg3In2Te6 matrix owing to the orientation attachment mechanism. Based on the results, it is believed that the formation of the AuTe2 phase is likely to introduce additional energy level in Hg3In2Te6, leading to the upward of band bending and increment of SBH.