Abstract: Pueraria root residue from pueraria starch manufactory contains definite amount of isoflavone which is a kind of phytoestrogen with important physiological effects. Pueraria root residue was used as the main material for solid-state fermentation by Aspergillus niger ZU-01 strain. Xylanase and endo-β-glucanase(CMCase) produced from solid state fermentation could hydrolyze the cell wall's fibre of pueraria root residue, thus improving the yield of isolavone. Optimized culture medium of solid-state fermentation was composed of 70% pueraria root residue and 30% wheat bran, with 70% water content. After 120 h fermentation at the temperature of 30℃, the yield of total isoflavone reached 1.82 times as that by normal ethanol extraction. HPLC showed that the content of daidzein decreased while the content of isoflavone glucoside increased after fermentation. A 70% higher content of puerarin which reached 3.97 mg/g pueraria root residue was gained comparing to that of normal ethanol extraction.