Abstract: Marine oil spill frequently occurred and the application of chemical dispersants is one of the common emergency methods to treat spilled oil.Marine spilled oil and SPM(suspended particle material) can interact with each other and form OSAs (oil-SPM aggregations), and they can also interact with particle material, phytoplankton, bacteria and bioclastic to form MOS(marine oil snow).Application of dispersants will influence the formation of these two aggregates, and affect the transport and fate of spilled oil.The applying rules of dispersant and the present situation of the dispersant application on spilled oil are introduced in the paper.After analyzing the formation mechanism of OSAs and MOS, the influence of dispersant application on the interactions between marine spilled oil and suspended particles were analyzed, and the environmental fate of OSAs and MOS were discussed.