Method for purifying anidulafungin precursor compound

The invention discloses a method for purifying an anidulafungin precursor compound. The method comprises the process steps of flocculation, acidification, filter pressing, nanofiltration, purification, salting-out and recrystallization. The method mainly comprises the following steps of adding kieselguhr to a fermentation conversion liquid, stirring, flocculating, adjusting the pH by using hydrochloric acid, carrying out plate-frame filter pressing, collecting filter pressing filtrate, and carrying out low-temperature nanofiltration concentration on the filter pressing filtrate; adding methyl tertiary butyl ether or petroleum ether to a nanofiltration concentration solution for stirring and extracting, removing an organic phase of an impurity, and adding methanol or ethanol or a little of sodium chloride in a water phase for crystallization; and repeating a crystallization process and carrying out recrystallization to obtain the anidulafungin precursor compound. The method has the advantages that extraction i