Raman spectroscopy was used to study the influence of ultraviolet-A(UV-A) radiation on collagenⅠ. The Raman spectra of collagenⅠ and that after 90 min UV-A radiation were reported. The results proved that irradiation with 90 min UV-A caused the change in the structures of collagenⅠ. Intramolecular hydrogen bonds were broken, and the hydrogen bonding system was changed. The intensity of helix was decreased, while the intensity of the disordered conformation in proteins such as random coil was increased. Otherwise, the UV-A radiation influenced the hydroxylation of proline and the content of hydroxyproline was reduced. The changes caused by UV-A radiation could damage the triple helical structure of collagenⅠ. It would lead to a series of changes, such as the destruction of collagen fibers during the photoaging of skin.