Brown sugar (non-centrifugal cane sugar) is popular for its pleasant caramel-like aroma and sweetness. Vacuum simultaneous steam distillation and extraction (V-SDE) and gas chromatography-mass spectrometry (GC-MS) was used to study the volatile fraction of brown sugar. To further determine the aroma-active compounds in brown sugar, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) were used in conjunction with aroma extraction dilution analysis (AEDA), odor activity values (OAVs), and sensory evaluation to analyze the effects of the key aroma-active compounds on sweetness. A total of 37 aroma-active compounds were obtained, mainly including ketones, pyrazines, alkanes, phenols and alcohols, which contributed caramel, sweet and fruity notes to brown sugar. Among them, furfural, benzeneacetaldehyde, 2,3-butanedione, β-damascenone, 2-methoxyphenol, dihydro-2-methyl-3(2H)-furanone, 2-furanmethanol and butyrolactone could significantly enhance the sweetness of sugar solution because of the congruency of the aroma attributes and sweetness.