Oysters have strong pollution tolerance; it can survive well in polluted waters. When oyster grows in polluted water, its meat can accumulate heavy metals, which has considerable potential for water clarification. Besides, oyster has very thick calcium carbonate shells, during shell growth; it can absorb and fix CO2, which is also known as an important portion of greenhouse gases; so the oyster culture is able to provide benefits of CO 2 reduction. In view of this, we attempted to carry out a pilot oyster culture experiment in the Er-Ren estuary, where located in Southwest of Taiwan. The main purposes of this experiment are to assess the efficiency of water clarification and CO2 reduction by cultured oyster. Preliminary result reveals: the Er-Ren estuary cultured oysters have very high efficiency in Cu and Zn absorption, the Cu concentration in mature oyster meat could reach 34,496 times higher than it in the water of Er-Ren estuary; and Zn concentration could reach 83,500 times. On the aspects of CO2 absorption, after measured oyster shell growth rate, we roughly estimated the CO2 fixing rate is 0.78 kg/m2/day in the Er-Ren estuary oyster culture experiment.