Dioxin is the most toxic chemicals known at present, it is usually generated in combustion and industrial production processes, and it is difficult to degrade, therefore, it′s particularly important for its detection. Infrared spectroscopy can retrieve component concentration based on infrared absorption characteristics of molecules, which has been widely researched and applied in small molecules. At present, there is no information about the parameters of dioxin infrared spectrum, in order to measure the concentration of dioxin by spectroscopy, firstly, we need to study the spectrum of dioxin. The spectral calculation of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) molecule is carried out with Gaussian 09 software package. The VERTEX 80 Fourier transform infrared spectrometer is used to measure the 2, 3, 7, 8-TCDD molecule spectrum in the range of 1600-1000 cm-1 under different concentrations of 30 μg/mL, 40 μg/mL, and 50 g/mL, respectively. The resolution of the instrument is 4 cm-1 and the scanning times is 16. In addition, the spectral intensity of 2, 3, 7, 8-TCDD molecule at 1466 cm-1 is measured at 297 K. The results show that the maximum absorption peak of 2, 3, 7, 8-TCDD molecule is located near 1466 cm-1, this is caused by the vibration of benzene ring. It has good correspondence of spectra obtained by theoretical calculation and experiment. This study provides spectral information for the measurement of 2, 3, 7, 8-TCDD molecule concentration by infrared absorption spectrometry, and has important theoretical significance.