The present invention discloses a medicament useful for treating aseptic inflammations, containing anemonin as an effective ingredient, and use of the anemonin compound in treating aseptic inflammations. The effective ingredient in the present medicament, anemonin, can be extracted and separated from natural plants containing anemonin or its precursor. The present invention also discloses a method for preparing anemonin extract. The present medicament can be formulated into preparations for oral administration, injection and topical application, especially liquid extract, plaster, suppository, liniment, and paint etc., which can be transdermally absorbed.