Disclosed is a method for preparing a vegetable oil emulsion including mixing water with a vegetable oil to provide a first mixture (a), and applying ultrasonic waves with a frequency of 25 to 70 kHz to the first mixture to solubilize the first mixture (b). Through treatment of ultrasonic waves with a certain frequency, the method for preparing a vegetable oil emulsion according to the present invention has advantages of significantly easily converting various herbal oils into aqueous emulsions at a high yield, significantly preventing layer-separation between oils and water for a long time, and being widely applicable to a variety of herbal oils.
