Biological functions of biological organic molecules must be achieved in their solutions. Terahertz wave is very sensitive to water and it can detect changes of the water dynamics of biological molecules directly in hydration layer between water and solute molecules. Thus, Terahertz Time Domain Spectroscopy(THz-TDS) technology is an ideal tool for the detection and research of biomolecular organic solutions. In this paper, THz-TDS is used to research the molecular structures of glucose. The absorption spectrum of glucose and its solutions of various concentrations are obtained by THz-TDS and Fourier Transform Far Infrared(FTFIR) spectrometer in nitrogen or vacuum environment at room temperature, respectively. The results show that distinct characteristic absorption peaks of glucose solutions are found at far-infrared range. Solutions of glucose with different concentrations show different absorption to terahertz wave. In consideration of works above, THz-TDS can provide a new method to identify glucose and its solutions of various concentrations.