The present invention relates to a method for preparation of androst-4-ene-3,17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD). More particularly, the present invention relates to a method for preparing AD/ADD, comprising the steps of: (a) heating sterols and emulsifier respectively, to dissolve completely and mixing to prepare a mixture; (b) placing the mixture in a water bath at 70.about.90.degree. C. and stirring to obtain emulsified sterols; and (c) adding the emulsified sterols to culture media of microorganism as a component. And the present invention relates to a method for preparing AD/ADD, comprising the addition of cyclodextrin-sterol complexes extracted from milk to culture media of microorganism as a component. The emulsified sterols and cyclodextrin-sterol complexes adopted in the present invention can be easily prepared and be effectively used for obtaining AD/ADD at a high yield.