Abstract: According to the geometric modelling of the surfactant packing at the interface,it was concluded that a co-solvent(hexanol)has to be added to the organic phase in order to establish a CTAB reversed micellar system. It seems that the partition of BSA between two phases depends not only on the content of co-solvent in organic phase,but also on the pH value,the concentration and species of ion in aqueous phase. The experimental results lead to the conclusion that the major driving force in the protein extraction is electrostatic interaction.