Poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) is a stimuli-responsive polymer whose phase transition in solution is influenced by the temperature and the pH of solution. In this presentation, we report on our recent results of the all-atomistic molecular dynamics simulation for the coil–to–globule transition of PDMAEMA. In the structural analysis, a single chain of PDMAEMA shows the coil-to-globule transition in aqueous solution from below LCST to above LCST. The hydrogen bond and local dynamics of water molecules near the PDMAEMA chain provides atomic-level insights into the role of each functional group in PDMAEMA for the coil-to-globule transition.