Abstract: Since the last century, marine plastic debris, as a category of pollutants with potential ecological risks, have attracted the attention of researchers. As large as several meters or as small as a few microns, plastics are widely distributed in the marine environment. Compared with dissolved pollutants, it is more difficult for plastics to disperse evenly in marine media for they existed in solid form for a long time in marine environment. However, in recent years, plastic debris have been found in the ocean, polar and deep sea where are far from their sources, which is obviously closely related to the transport of plastics in the marine environment. On the one hand, the distribution and transport of plastics are affected by their material properties and various environmental factors. Therefore, it is necessary to understand and consider these factors in designation of marine plastic monitoring activities to improve effectively the sampling representativeness by adjusting and standardizing the sampling scheme. On the other hand, understanding the factors affecting the transport and fate of marine plastics is also a necessary prerequisite for predicting whether plastics will accumulate in specific sea areas or layers and where they would accumulate, for inferring the exposure of plastics in marine habitats, and then for predicting the potential risks of plastics to ecosystems and even human health. Base on relevant researches summarized on the transport behavior of plastics (including microplastics), the factors affecting the horizontal and vertical distribution of marine plastics, and the sampling methods in plastic monitoring activities in seawater and sediments are discussed. According to the research progress related to plastic environmental behavior, the schematic basis and precautions during formulation of plastic debris monitoring activity are analyzed.