Based on the seawater and sediment monitoring results of Shengsi Lvhua Island’s mariculture zone in spring, summer, autumn of 2011, the results showed that, mariculture zone’s water temperature, salinity, pH, chemical oxygen demand (COD), dissolved oxygen (DO) , dissolved inorganic nitrogen (DIN) and chlorophyll a(Chl.a) changed with the seasons, eutrophication of the mariculture zone was serious, and the eutrophication level was spring＞summer＞autumn；the sea water’s organic pollution level (A) in summer was the lowest, but attained lightly polluted level in spring and autumn. The seawater environment was mainly affected by the Changjiang River, breeding pollution and so on, and the higher level of dissolved inorganic nitrogen was the main reason for eutrophication and organic pollution, and was also a reason of the area’s high incidence of the red tides. The content of mercury (Hg), arsenic (As), copper (Cu), lead (Pb), cadmium (Cd), chromium (Cr) in sediments (6 kinds of heavy metal) accorded with the first class of the marine sediment quality of National Standards. According to the Hakanson’s evaluation method, the potential ecological risk was low, but the content of chromium (Cr) reached medium pollution level, so monitoring should be strengthened.