An online gel permeation chromatography-gas chromatography/mass spectrometry (GPC-GC/MS) method was developed for determining volatile compounds in different parts of Panax quinquefolius L. (American ginseng). First, samples were extracted by accelerated solvent extraction (ASE), and the optimum ASE operations were dichloromethane as extraction solvent, 100 degrees C of extraction temperature and 7 min of static extraction time. Then the compounds with important bioactivities were purified, isolated and monitored by online GPC-GC/MS system. In total, twenty four volatile compounds were characterized in the four parts (root, stem, leaf and flower) of American ginseng. The main components in root and stem were 10,12-Octadecadienoic acid and Falcarinol, respectively; for leaf and flower, 9,12-Octadecadienoic acid was the major component. It was indicated that the combination of ASE technique and online GPC-GC/MS system was a rapid extraction, purification, determination and characterization of volatile compounds in root, stem, leaf and flower of American ginseng.