Abstract: In order to improve the yield of aleuritic acid, the lac saponification waste liquid left in the preparation of aleuritic acid by the factory was used as raw material to recover aleuritic acid by configuration conversion method through salting out, acid analysis, decolorization, recrystallization and other steps. The configuration conversion process of aleuritic acid was optimized by single factor experiment, and the structure of aleuritic acid was analyzed by nuclear magnetic resonance, mass spectrometry, infrared and thermogravimetric analysis. The configuration analysis of aleuritic acid was carried out by differential scanning calorimetry and C18 column resolution by high performance liquid chromatography. The results showed that the recovery of aleuritic acid by configuration conversion method could improve the yield of aleuritic acid. The optimal preparation conditions were determined as the ratio of solid to liquid of raw material and concentrated hydrochloric acid of 3:5(g: mL), reaction temperature of 100℃ and reaction time of 7 h, and the amount of active clay was 10% of the quality of the crude aleuritic acid. After decolorization and recrystallization with 20% ethanol solution for two times, the yield and purity of aleuritic acid were 3.78%±0.5% and 80.65%±0.41% respectively. The results of structure and configuration analysis of the product showed that the product prepared by this method was erythron aleuritic acid. The eleostearic acid prepared by this method came from waste and had fewer impurities after refining, so it could effectively improve the yield of aleuritic acid.