Effects of thermal treatment temperatures from 323 K to 473 K in air atmosphere on the Au/CdZnTe contacts fabricated by thermal vacuum evaporation was investigated systematically. The results show that the optimized performances of the Au/CdZnTe contacts after thermal treatment in air at a range of 353-373 K can be obtained, that is, the contacts possess lower barrier height, smaller contact resistance and better ohmic coefficient, without damaging bulk CdZnTe properties. Nevertheless, performing thermal treatment over 400 K, the deposited surface of Au electrodes will grow worse apparently, and the leakage current of CdZnTe samples enhances significantly. This might be attributed to the increase of the Cd vacancies produced by Cd sublimation from the CdZnTe into air atmosphere with the increase of temperature.