Peeled walnut kernels are popular among consumers for their easy consumption, wide application scenarios and excellent flavor, of which flavor is an important index for evaluating walnut quality. To study the key flavor substances of peeled walnut kernels, three varieties of walnut raw materials (Qing Xiang, Wen 185 and Da Pao) were selected for peeling and low temperature roasting, and sensory evaluation analysis was carried out by nine-point scale method, and volatile flavor compound of peeled walnut kernels were analyzed by gas chromatography-olfactometry-mass spectrometry. The results indicated that the peeled walnut kernels showed an overall sensory taste of fatty, sweet and creamy flavor with low bitterness. A total of 25 volatile flavor compounds, including 6 aldehydes, 2 ketones, 9 alcohols, 2 esters, 4 hydrocarbons, 1 furan and 1 ether, were detected in three varieties of peeled walnut kernels by headspace solid phase microextraction. The nine key flavor components, including hexanal, octanal, nonanal, furfural, benzaldehyde, 1-hexanol, 1-pentanol, 2,3-butanediol and 2-heptanol, were further clarified using solvent-assisted flavor evaporation combined with olfactometry to give the walnuts a raw green, fatty, burnt and sweet flavor. Correlation analysis was performed between the nine key flavor components and sensory attributes, and it was found that nonanal, hexanal, 2-heptanol, 2,3-butanediol and 1-pentanol were the key substances causing sensory differences in walnuts of different varieties. The results of this paper provided important support for the improvement of the flavor quality of walnut kernels and the creation of peeled walnut kernel snacks.