The present invention provides an HTFS system for quickly preparing and evaluating, at low cost, an SEDDS formulation containing ingredients in a viscous liquid state or in a semi-solid or solid state. More specifically, the present invention provides a method for formulation designing of a self-emulsifying preparation, comprising the steps of: (a) diluting, in a diluent solvent, each of ingredients in a viscous liquid state or in a semi-solid or solid state to prepare each dilution containing the constituent ingredient and (b) preparing plural test mixtures by dispensing the ingredients contained in the dilutions and ingredients other than those ingredients into plural test vessels so that the kinds and mixed amounts of the ingredients and the other ingredients added differ among the test vessels.
