The invention discloses a preparation method for trifluoroacetylacetone by a two-stage method. Firstly, a trifluoroacetate is reacted with acetone to obtain a enol sodium salt under the effect of sodium methylate and/or sodium ethylate; and secondly, the enol sodium salt is subjected to acidification, and then reduced pressure distillation is carried out, so that the trifluoroacetylacetone is obtained. The preparation method disclosed in the invention has the characteristics that the product yield is high, the method is safe and friendly to environment, the process is simple and the like.