Abstract: The aim was to study the influence of 3 factors including extracting temperature, extracting time and liquid-solid ratio on the yield of SDF from Eucheuma carrageenan residue by response surface methodology.On the basis of single-factor investigation and Box- Behnken central composite experiments, the processing technology of SDF extration was optimized, and the extracting factors effection on yield of SDF was analyzed by response surface experiments.The results showed that the extraction rate was significant effected ( p < 0.05) by different levels of 3 factors; and there was significant interaction influence ( p < 0.01) on extration rate between extracting temperature and liquid-solid ratio and extracting time; and a negative linear correlation was found between critical values.Taking the maximum rate of SDF extraction as response value, the optimizing process parameters were determined to be: extracting temperature 90℃, extracting time 3.2h, liquid- solid ratio 85mL /g.Under the optimal condition, the extraction yield of SDF from residue was 5.035% ± 0.036%.The processing technology could provide feasible guidance for the recycle of Eucheuma carrageenan residue.