Vacuum ultraviolet circular dichroism (VUV-CD) spectra of proteins in solution have been measured using synchrotron radiation vacuum ultraviolet circular dichroism spectrometer and a special cell. The measurement wavelength is down to 175nm. A new calculation method has been applied for calculating the content of five kinds of secondary structures of proteins. Their results are coincident with that from X-ray diffraction method. In order to get good VUV-CD spectra, several important factors have been discussed. The experiments show that so far. VUV-CD analysis is one of the favorable method for secondary structure studies of proteins.