Abstract: The research of spectral characteristics of the four following sorts of vitamins including riboflavin,folic acid and vitamin K1 and K2 in the terahertz broadband frequency range using fourier transform infrared spectrum(FTIR)technique is presented.By respectively mixing the four sorts of samples and polyethylene in different ratios,the absorption spectra of each was analyzed.Besides,absorption spectra in different ratios of the mixture were compared,thus the detailed spectrograms were presented.The results showed that the concentration increment of riboflavin and folic acid samples had negative effect on their absorption repeatability in the range of high frequency,which evidenced that the absorptivity of the vitamin samples increased with the frequency increment.However,the phenomenon did not existed in vitamin K1 and K2 because of the low absorptivity of the both.Broadband terahertz fingerprint spectra obtained in this study provide reliable data reference for vitamin in the study of terahertz spectrum database,and basis for rapid,nondestructive identification of vitamin drugs molecule.