The microstructures of the middle-phase microemulsions were studied by using ESR and NMR techniques. The results from the two methods show that the microstructures of the middle-phase microemulsions undergo the change from O/W to bicontinuous(BC), and to W/O with the variation of NaCl concentration, and BC structure includes O/W and W/O. The models of the bicontinous structure were constructed on the base of the studies.
