Abstract: Chemical substances of Magnolia officinalis were extracted by supercritical CO₂ method. The extract was analyzed by capillary gas chromatography combined with mass spectrometric detection (GC/MS). In the mass spectra of both magnolol and honokiol, the both molecular ion peaks at m/z 266 (M^•+) are the basic peaks. The main fragment peaks at m/z 237, 184, 165, 91, 77 are the same. But the fragment peak at m/z 247 is the typical characteristic of the mass spectra to differentiate the chemical structures between magnolol and honokiol.