To study the posts-depositional behaviors of organic pollutants in natural conditions, concentrations and distributions of free and bound PAHs in a sediment core from Nam Van artificial Lake of Macao were investigated. Result indicate that free PAHs are predominated by 4-ring, 6,7-ring, and 5-ring PAHs, with the mass percentages of 28.7% to approximately 40.6%, 17.6% to approximately 29.6%, and 13.2% to approximately 28.2%, respectively, and for bound PAHs, the main components are 4-ring, 3-ring, and 2-ring ones, with mass percentages 42.3% to approximately 55.8%, 20.2% to approximately 35.8%, and 7.8% to approximately 18.8%, respectively, which suggeste that PAHs with low molecular weight are more prone to entering the micro-pores of sediment organic matters. Vertical profile of free PAHs concentrations in sediment core, to some degree, is correlated with the degree of regional economy development and the proceeding of environmental management. The concentrations of bound PAHs in the sediment core are controlled by the total PAHs mass input to the sediments and the structure (especially the polymerization) of sediment organic mater. The sediment burying favors the transformation of free form to bound form for PAH compounds.