Water is the source of life, but the effects of hydration water on the dynamics and function of biological and bio-compatible macromolecules are still full of debates. Chen et al. found a dynamic transition of the solvation water at about 220 K, and claimed that such a liquid-liquid transition of water command the dynamic and function of the proteins. However, Hong and colleagues found out that dry perdeuterated protein also experience a dynamic transition at about 200 K by quasi-elastic neutron scattering. To clarify the problem, a direct observation of the dynamics of the hydration layer about macromolecule in the transition process is crucial. Here, we propose quasi-elastic neutron scattering of dry Poly(ethylene glycol) (PEG) and PEG solvated with a single layer of water bellow and up the liquid-liquid transition of confined water at about 200 K.