AIM:To extract pueraia isoflavone and soyisoflavones with n-butanol by means of inner ebullition from Radix puerariae lobatae.METHODS:A little ethanol was first used to saturate the powder of Radix puerariae lobatae to make the pueraia isoflavone desorbed adequately,and then hot n-Butanol solution was added to make the ethanol inside Radix puerariae lobatae begin to boil and the extraction was intensified.Based on different solubility of pueraia isoflavone and soyisoflavones in n-Butanol,when solvent vaporized,the soyisoflavones were separated and then the pueraia isoflavone by step vaporizeing on centrating crystal.RESULTS:80 mL of 60% ethanol,saturating time 20 min,600 mL n-Butanol including 20% water,at the temperature of 90 ℃,the yield of total isoflavone was 11.3 %.When 90% solvent vaporized,the ratio of quality of the soyisoflavones and pueraia isoflavone was 1∶3.The puerarin and daidzin's purity reached 46.0% and 6.12% by the HPLC respectively.CONCLUSION:The technology of inner ebullition extraction and solvent vaporizing crystal separation are simple,which provide industry production basis for pueraia isoflavone and soyisoflavones.