The invention discloses a preparation method of posaconazole. The preparation method of the posaconazole is characterized in that jellylike solids are separated out, a mass volume ratio of the posaconazole to a mixed solvent is within 1: 8-1: 10, g/ml in unit, a volume ratio of alcohols to esters in the mixed solvent is from 1: 8 to 1: 20, a volume ratio of the mixed solvent to alkane or aromatic hydrocarbon is within 1: 2-1: 3, and the alcohols in the mixed solvent refer to one of C1-C4 alcohols. The preparation method of the posaconazole has the advantages that since the solubility of the posaconazole in the alcohol and ester mixed solvent increases along with temperature change, the alcohol and ester mixed solvent at 40 DEG C-75 DEG C is dropwise added into an alkane, naphthenic hydrocarbon or aromatic hydrocarbon solvent within 5-20 minutes, and complete amorphous posaconazole cannot be obtained when a crystallization temperature surpasses 80 DEG C during drop-by-drop addition; solvents used in the whole process are low-toxicity class-3 solvents of organic solvents, and accordingly the preparation method is high in safety.