In order to determine the key aroma compounds in leg from Beijing roasted duck， the aroma compounds in leg skin and leg meat from 4 most representative Beijing roasted ducks were analyzed qualitatively and quantitatively by using headspace solid-phase microextraction / gas chromatography-olfactometry-mass spectrometry（HS-SPME-GC-O-MS）. The key aroma compounds were detected based on odor activity value（OAV） and contribution rate， and were confirmed by flavor recombination， omission experiments and triangulation test of sensory evaluation. The results revealed that 41 aroma compounds in leg skin and leg meat from Beijing roasted duck were determined， including aldehydes， sulfur-containing compounds， alcohols， furans， acids and phenols. 18 aroma compounds higher than 1 in OAV were detected， among which 2-furfurylthiol （32.62%-72.04%） and dimethyl trisulfide （24.18%-52.03%） had the highest contribution rate. The results of flavor recombination， omission experiments showed the 2-furfurylthiol and dimethyl trisulfide significantly affected the flavor of leg skin and leg meat in Beijing roasted duck（P<0.01）. Meanwhile methional， hexanal， heptanal， octanal， nonanal， （E， E）-2，4-decadienal and 1-octene-3-ol also significantly influenced the flavor of leg skin and leg meat in Beijing roasted duck（P<0.05）. The characteristic aroma was fatty， roasty and meaty flavor in leg skin and leg meat from Beijing roasted duck. The leg skin had richer fatty aroma than leg meat. Meanwhile， leg meat had richer roasty aroma. The key aroma compounds of leg skin and leg meat in Beijing roasted duck were 2-furfurylthiol， dimethyl trisulfide， methional， hexanal， heptanal， octanal， nonanal， （E， E）-2，4-decadienal and 1-octene-3-ol.