Abstract: The extraction process for pitaya seeds oil via supercritical carbon dioxide was optimized by response surface methodology (RSM), the test data were analyzed by software Design Expert and the chemical compositions of pitaya seed oil was analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that supercritical CO2 extraction process were impacted significantly by extraction time, pressure, and temperature; the optimum extraction parameters were extraction pressure at 25 MPa, extraction temperature at 40 ℃, and extraction time for 3.5 h the oil extraction yield was 30.21%. The main fatty acids of pitaya seed oil were unsaturated fatty acids, which accounted for 74.64% of total fatty acids, and linoleic acid and its isomer were 46.91%, oleic acid and its isomer were 25.36%; saturated fatty acids were dominated by palmitic acid, and palmitic acid and its isomer consisted of 21.10%. Pitaya seed oil can be used as healthy oil for development.

Key words: pitaya seed oil, supercritical carbon dioxide extraction, response surface method, gas chromatography-mass spectrometry (GC-MS), fatty acid, physical and chemical properties