Method for preparing amorphous-form Romidepsin

The invention relates to a method for preparing amorphous-form Romidepsin. The method comprises the steps that Romidepsin is dissolved in an alcoholic solution, water is added, the mixture is stirred to be uniform before being put in a pre-cooled freeze-drying bin, and lastly pre-freezing and drying are conducted to obtain amorphous-form Romidepsin. According to the method, technological operation is simple, cost is low, and prepared amorphous-form Romidepsin is good in stability and quite suitable for industrial production.