We make a detailed analysis on the linearity and accuracy of the relationship between the full-width at half-height (FWHH) of the atmosphere molecules Rayleigh scattering spectrum and the square root of the atmospheric temperature. A simulation of the FWHH of the atmosphere molecules Rayleigh scattering spectrum is made based on the S6 Atmosphere Model and U.S. Standard Atmosphere Model. The calculated temperature is compared with the initial simulation temperature. The result shows that the FWHH of the atmosphere molecules Rayleigh scattering spectrum is nearly proportional to the atmospheric temperature. The goodness-of-fit index of the fitting curve is 0.9977 and the maximum absolute error of measured atmospheric temperature is about 2 K.