In order to provide a theoretical guidance for the selection of salting-out agents and extraction agents， the ionic salvation free energies of eleven kinds of salts and three kinds of solvents in 10% 2，3-butanediol model fermentation solutions were calculated based on the scaled particle theory，with the corresponding extraction effects being ranked according to the experimental extraction results obtained at 37 ℃ ． It is found that，in the several parts consisting of the standard molar solvation free energy，the electrostatic free energy between the salt and the solvent，whose larger absolute value means better salt extraction effect，is the key factor affecting the extraction; and that，with the increase of absolute value of the standard molar solvation free energy，the mass fraction of 2，3- butanediol increases linearly，while that of water decreases linearly