The invention discloses a method for preparing 4,5-epoxy-17beta-hydroxyl-androstane-3-ketone. The method comprises the following steps of: in the presence of ionic liquid shown by a formula(II) and magnesium oxide, testosterone shown by a formula(I) and hydrogen peroxide solution are reacted at the temperature of between 0 and 60 DEG C, using TLC to detect and track a reaction end point, and after the reaction is finished, performing separation treatment of reaction solution to obtain the 4,5-epoxy-17beta-hydroxyl-androstane-3-ketone shown by a formula(III), wherein the mass ratio of the testosterone to the hydrogen peroxide (H2O2) is 1:2-10. Compared with the prior art, the method has the advantages of easy operation, mild reaction conditions, few three wastes, easy and convenient post-treatment operation and reuse of the ionic liquid and the magnesium oxide, and is a green, environmental-protection and pollution-free production technology which is economical, practical and environmentally-friendly.