The analysis of quality and extraction of soluble dietary fiber(SDF) from tea dust by alkali treatment were investigated.The results showed that the optimum conditions of extraction were obtained on the basis of single factor and orthogonal test: NaOH concentration 8%,temperature 90℃,time 75 min.The effect of temperature was the most significant,followed by NaOH concentration and time.The amounts of NO2-absorbed by SDF at pH 2.0 were 19.70 μmol/g,significantly higher than that at pH 7.0(15.83 μmol/g),while the amounts of cholesterol absorbed at pH 2.0 was 71.28 g/g and 82.09 g/g at pH 7.0.The data indicated that the characteristic of SDF extracted from tea dust is perfect,and it will have the potential using in the healthy food products.