To explore the impact of dredged materials upon the marine ecological environment, surveys of water quality, sediments and marine organisms were conducted respectively at seventeen sites in Lianyungang dumping area and nearby waters in March, 2014. For the sake of study the sea area was divided into dumping zone, external dumping zone and mariculture zone. Marine pollutants and biological indicators of the three zones were compared in pairs with an aim to explore the status quo of phytoplankton, zooplankton and benthic communities and the differences in between. Hence a more comprehensive evaluation can be made over the impact of dredged materials upon the marine ecological environment. The survey results were presented as follows: (1)Dredged materials constituted the major source of heavy metals in the dumping zone, and exerted influence upon the external dumping zone under the diffusion effect. The heavy metals content in seawater and sediments ranked as dumping zone>external dumping zone>mariculture zone. (2) Indicators like chlorophyll a and phytoplankton did not differ much among the three zones, which implied that phytoplankton were not seriously affected by dredging activities. (3) By comparison the benthos in dumping zone displayed fewest species, relatively lower habitat density and biodiversity index, which indicated the obvious change in ecological environment and apparent negative impact from dredged materials in the zone.