Abstract: This study is aim at confirming the key stage where the formation of volatile constituents in the headspace above domestic whisky takes place. The static headspace gas chromatography-mass spectrometry was employed to analyze the volatile constituents in the headspace above each production stage. The principal coordinates analysis was used for the selection of classification criteria for the beverage in each stage, after which the orthogonal partial least square discrimination analysis was utilized to establish the classification model. The results showed that volatile constituents in the headspace varied significantly in different stages (α=0.05), and that the soaking was sufficient to be the classification criteria. Altogether 17 key differential components, including 11 introduced by oaks during soaking and aging, were found in samples before and after soaking. The 11 oak introduced components, except acetic acid, butyraldehyde, and heptadecane, contributed to the aroma of the whisky. Meanwhile, dimethyl sulfide, furan, ethyl hexanoate, butanol, 2-methylproapn-1-ol, and n-propanol were reduced after oak soaking. Obviously, the key stage was soaking in the formation of volatile constituents in the headspace above domestic whisky.