Using purity,yield and average particle diameter of LOA as key indicators,various strategies of solventing-out crystallization of LOA,such as crystal seed addition,feeding rate and volume of antisolvent were studied.The process of the crystallization of LOA was divided into five stages based on the solubility curve of LOA in the ethanol / water system.The results showed that the crystalline growth was improved if 4% crystal seeds were added when the volume ratio of ethanol to LOA solution was 0.8 and the adding rate of ethanol in stage Ⅲ appropriately slowed down.The crystallization purity was 97.9%,and the average particle diameter was 270.6μm.