Terahertz time-domain spectroscopy (TDS) has been used to study the spectral properties of tyrosine at room temperature. The terahertz spectra of sample were observed. The result shows that the sample has the spectral response in terahertz spectral range, a fact demonstrating that the terahertz spectra of tyrosine could be used to study the molecular structure and vibration of sample. Two absorption peaks were found at 0.23 and 2.46 THz respectively for the first time. The corresponding theoretical spectra were given by using HF and DFT methods for both tyrosine monomer and dimmer. The difference between the theoretical and experimental results was analyzed in detail. The origin of the observed absorption at 0.23 THz was assigned to the wagging of the two tyrosine molecules linked by hydrogen bond.