Fractional composition of surface and core sediment samples were analysed to collect quality improvement and weed control in eutrofied brackish Lake Kyungpo. Fractional scheme for sediment phosphorus was made for four chemically defined phosphorus forms as adsorbed phosphorus, nonapatite inorganic phosphorus, apatite phosphorus and residual phosphorus. The analysis of surface sediment samples shows that Lake Kyungpo sediments have high labile phosphorus fraction and thus have high water pollution potential. It was found that no significant water quality improvement could be expected by dredging down to 1.0m depth of sediments.