In this study, the essential oil of aerial parts of a species of a plant called Ferulago Angulata was extracted by CO2 to optimize the results of the supercritical extraction process and then the essence was analyzed by the method of GC/MS. This extraction has been performed using Taguchi testing method and choosing L16 array in a laboratorial pilot under the following: pressure (90,120, 140, and 190 bar), temperature (35, 40, 45, and 55 degrees C), the average particles size (250, 500, 710, and 2000 mu m), flow rate (3, 5, 7, and 12 ml/s) and dynamic time (25, 50, 70, and 120 min). Then optimizing process was done to achieve maximum yield extraction. The optimizing conditions are as follows: 190 bar, 35 degrees C, 710 mu m, 12 ml/s, supercritical flow rate 12 ml/s and the final yield is 0.853%. The total yield of supercritical extraction in the mentioned conditions as well as empirically is 0.97% or about 1%. This is the first report announcing optimization of the operation of supercritical extraction of Ferulago Angulata in a laboratorial condition. In the last report of the same authors, which was also for the first time, the chemical components of this plant essence were identified through supercritical extraction and then were compared with the extraction components of other traditional methods. (C) 2011 Elsevier B.V. All rights reserved.