The hydration shell layer of DNA plays a crucial role in its biological function and its structural characteristics are significantly influenced by the DNA sequence. Different DNA sequences not only alter the interactions within the molecule, but also influence the dynamics of the hydration layer around it. In recent years, terahertz spectroscopy, as a non-invasive detection technique, has shown great potential in probing the rotational and vibration properties of biological macro-molecules. Especially in the low-frequency terahertz band, the vibration spectra of DNA and its hydrated shell layer can reveal subtle changes in the molecular structure and its interaction with the hydration environment. Our study shows that the hydration shell layer caused by DNA sequence differences exhibits characteristic absorption peaks in low-frequency terahertz spectra. These absorption peaks are closely related to the vibration modes of DNA and its collective behavior in the hydrated state. By analyzing these terahertz spectroscopic data, we can gain insight into the structure of the DNA hydration shell layer and its variation with sequence. In addition, this approach has the potential to be applied to understanding disease mechanisms and drug development. By accurately characterizing the DNA hydration shell layer and its structural changes, we can better understand biological processes at the molecular level and provide important experimental data for research in related fields.