Protein denaturation is not only one of the basic problems in biophysics and biochemistry, but also a practical one in applications. It is undoubtedly useful to explore new methods for detecting protein denaturation because they will surely provide some new information from new angles of view. For the first time, Sofar as we know we apply the reed-vibration mechanical spectroscopy for liquids (RMS-L) to measure the dehydration and denaturation process of egg white, one of typical protein hydrogels, in this work. The results show that there exist at least 4 remarkable processes of mechanical spectra with the reduction of water content. Based on the experiments and the analyses according to the relevant mechanical spectrum theories, the authors inferred that, with the water content reduction egg white may undergo the following 4 states successively: 1) bulk-like water protein hydrogel state; 2) bond water protein hydrogel state; 3) bond water and bonding protein mixed state; 4) bonding protein state. And the spatial configuration change of protein, namely degeneration, happens mainly in the mixed state in which the protein with bond water transforms to binding protein by losing the water. This means that the detection of dehydration and denaturation of egg white by RMS-L is effective, and we think the conclusions would also be reference materials for the deep studies of protein denaturation mechanisms and protein hydrogel states.