This paper analyzes phenolic compounds, carbon isotopes, and sugar components of whiskys based on the maturation period. For this, the paper considers a total of 40 whiskys(mainly imports) distributed in Korea. It is important to analyze the presence phenolic compounds(e.g., furfural, syringaldehyde, vanillin, syringic acid, and vanillic acid) because these are found only in whiskys ripened in oak. The results indicate that the total content of phenolic compounds increased with the increase in the storage period regardless of the type of whisky. In terms of vanillin/syringaldehyde(V/S), Scotch whiskys had 0.4～0.5; American whiskies, 0.30～0.34; and Canadian whiskies, 0.31～0.33. In terms of Scotch whiskys, Macallan had 0.25～0.34, making it unique among Scotch whiskys. In terms of the ratio of carbon isotopes, there were clear differences between malt Scotch whiskys, blended Scotch grain whiskys, American whiskys, and Canadian whiskys: －23.4～－24.3, －16.8～－21.0, －11.0～－11.5 and －9.5～13.9, respectively. In addition, malt Scotch whiskys contained 40～230 ㎎/ℓ of fructose; blended Scotch whiskys, 20～120 ㎎/ℓ; American whiskys, 50～70 ㎎/ℓ; and Canadian whiskys, 20～100 ㎎/ℓ, demonstrating that the fructose content of single-malt whiskys was twice the average fructose content. On the other hand, malt Scotch whiskys contained 30～170 ㎎/ℓ of glucose; blended Scotch whiskys, 20～120 ㎎/ℓ; American whiskys, 20～30 ㎎/ℓ; and Canadian whiskys, 10～110 ㎎/ℓ, demonstrating that the glucose content of single-malt whiskys exceeded the average glucose content. This study’s results can be used as a database of classification for whiskys based on the fermentation of raw ingredients and the period of maturation for distinguishing between different types of whiskys. In addition, the results can facilitate the verification of genuine whiskys by allowing for the identification of different types of whiskys based on the period of maturation.