Method for preparing essential oils

The invention relates to a method for preparing essential oils. The method comprises the following steps: taking and smashing raw materials; placing the smashed raw materials in an extraction kettle; carrying out supercritical extraction by taking a supercritical carbon dioxide fluid as an extractive solvent and taking alcohol with the volume concentration of 55 to 65 percent as an entrainer, wherein the extraction temperature is 25 to 38 DEG C, the extraction pressure is 15 to 22 MPa, the extraction time is 1.5 to 3 h, the ratio between the quality (Kg) of the raw materials and the volume (L) of the extraction kettle is 0.2 to 0.5 : 1, and the ratio between dose (L) of the entrainer and the volume (L) of the extraction kettle is 0.05 to 0.07 : 1; separating with a separation kettle to obtain an extract; placing the extract obtained through extraction in a molecular still; carrying out molecular distillation under the conditions of 0.3 to 0.5 Pa, 160 to 180 DEG C; and collecting to obtain a corresponding essential oil. The method can be used for extracting essential oils from various plants, so that compared with the prior art, the invention has the advantages of high essential oil yield and high contents.