Morphology and relaxation studies were very effective in understanding of the reverse osmosis (RO) permeation for the high-flux reverse osmosis (RO) membranes which were the thin-film-composite (TFC) type based on aromatic polyamide of m-phenylene diamine (MPD)/trimesoyl chloride (TMC). Microscopic morphology analyzed by atomic force microscopy (AFM) together with field-emission scanning electron microscopy (FE-SEM) and molecular relaxation characterized by solid-state H-1 nuclear magnetic resonance (NMR) spectroscopy revealed an important factor crucially affecting the enhancement of RO permeability, The proton spin-lattice relaxation in the rotating frame for the aromatic polyamides in their wet state (i.e., saturated with D2O) has been shown to be sensitive to the water flux and played a significant role in enhancing the membrane permeability, regardless of the surface features. The aromatic polyamide possessing relatively shorter spin-lattice relaxation times in the rotating frame, T-1 rho, provided a TFC membrane with higher RO permeation, and vice versa.