This article contains information about using Terahertz Time-Domain Spectroscopy (THz-TDS) and Fourier-Transform Infrared Spectroscopy (FTIRS) over the spectral region of 0.1− 3 THz for distinguishing and identifying three kinds of gramineous forage. The optical parameters such as refractive index, absorption coefficient and dielectric constant are obtained, which show that the spectrum of different forage varieties in the effective terahertz frequency range is different, and the absorption coefficient is monotonically increasing in the range of 0.2-1.4THz. The average refractive index and dielectric constant of the forage samples are located at the range of 1.5-1.8 and 2.3-3.0, respectively. And curves showed that there was a good discrimination between forage varieties. The study demonstrates that terahertz spectroscopy technique can be useful identification and diagnostic tool, which provides rapid, nondestructive discrimination of forage varieties.