The present invention relates to medical chemistry technique field, particularly relates to a preparation method for amorphous darunavir crystal, The present invention provides a preparation method for preparing amorphous form of darunavir using an anti-solvent method. It can be a different method compared to the evaporation and concentration process disclosed in WO2011048604. Although the same with WO2013114382, anti-solvent are used, the target crystal form are truly different. The crystal form of WO2013114382 is solvent-free darunavir crystal, while an amorphous form of darunavir in the present application.