The spectrum of temperature fluctuations was measured by micro-temperature and outer scale was obtained in duct. The results detector in duct. The distribution of C(2,n)and out scale was obtained in duct. The results of measurement show that some temperature spectra accord with von Karman's law in duct. The distribution of C(2,n)are given in duct. In the end,outer scale has little variety in duct.Therefore,managing the average of the wind speed,we must have taken into account the effect on the path weighting function by the distribution of C(2,n). Scintillation coming from refractive index fluctuations is more less than the measurement of scintillation in fact. Temperature fluctuations are not main source in scintillation in duct.