Preparation process for crystal form I of posaconazole

The invention discloses a preparation process for a crystal form I of posaconazole. The preparation process comprises the following steps: dissolving posaconazole in a mixed solvent of alcohols and esters, heating to 60-70 DEG C, dissolving, then lowering the temperature to 15-25 DEG C within 1-4 hours, crystallizing, and keeping the temperature to obtain the crystal form I of posaconazole, wherein the mass volume ratio of the posaconazole to the mixed solvent is 1:(4 to 20), and the volume ratio of the alcohols to the esters in the mixed solvent is 1:(2 to 30); in the temperature reduction process, the temperature of the mixed solution is reduced to 35-45 DEG C within 1-2 h, then a desolvation is dropwise added within 10 to 60 minutes, and the temperature is reduced to 15-25 DEG C after the adding is completed. The preparation process is convenient to operate, conducive to industrialisation and high in product yield; the used mixed solvent of the alcohols and the esters as well as alkanes or cyclanes belongs to less toxic solvents in organic solvents; the solvent recovery rate is high; the crystal form I of posaconazole can be stably obtained; the obtained product can be dried quickly.