Abstract: Dissolved organic matter (DOM) plays a key role in the marine biogeochemical cycle.Deciphering chemical composition and property of marine DOM is prerequisite to understand environmental behaviors of important biogenic elements (e.g., carbon and nitrogen).Recent development and application of advanced analytical techniques open a new window for chemical characterization of DOM at the molecular level.Compared to freshwater DOM, marine DOM not only has extremely low carbon concentration and complex chemical composition, but also is associated with high inorganic salt concentration.Some spectral techniques, such as ultraviolet-visible and three-dimensional fluorescence spectra, can analyze seawater DOM after filtration; however, the separation and enrichment of seawater DOM are required for high resolution analysis by mass spectrometry and nuclear magnetic resonance.In this review, we summarize the commonly used separation/enrichment methods, including solid-phase extraction (SPE), reverse osmosis/Electrodialysis (RO/ED) and ultrafiltration (UF), discuss the advantage and limitation of each method, and provide a perspective on future research direction of marine DOM.