Dynamic method was applied to measure the solubility of oil from Hippophae rhamnoides L. seed in supercritical CO2. The experiments were carried out at pressures and temperatures ranging from 10 to 30MPa and 303 to 323K, respectively. No marked changes in composition of extracted oil in the course of extraction were observed. The solubility was correlated with CO2 density and temperature by adjusting the constants of the del Valle-Aguilera equation. In order to enhance the extraction efficiency of supercritical fluid extraction (SCFE) for natural products, the SCFE process coupled with power ultrasound (20kHz, 150W) was investigated. The reactor with a power ultrasound transducer was specially designed and set up. For Hippophae rhamnoides L. seed oil, soybean seed oil, and licorice root oil extraction, the extraction rate and the oil yield were increased by 16.9-33.2% and 30% respectively, with the coupling of SCFE and power ultrasound.