Using the method of wavelet edge detection in the field of radiation temperature measure, two disp lacement formulae of inflexion wavelength justice are derived ou t through the relation of radiation energy, temperature and wavelenght and a new theory of the infrared wavelength thermometry is put forward. The theory proves three tempera-tures measured through infrared wavelength thermometry are consistent, they can be used to verify the black body, and it provides a new method for the infrared temperature measure.