In order to develop a new natural cigarette flavor, Undaria pinnatifida was respectively extracted by Soxhlet, microwave and supercritical CO₂ fluid extractions. The obtained extracts were analyzed by GC/MS and applied into cigarette as a flavor. The results showed that: 1) 49 components were identified and the major components were 29 - isofucosterol, methyl eicosa - 5, 8, 11, 14, 17 - pentaenoate, hexadecanoic acid, neophytadiene, oleic acid, tetradecanoic acid, linoleic acid, ethyl linoleate, octadecanoic acid, methyl linolenate; 2) the offensive odor and irritation of cigarette smoke was lowered, smoke sweetness was enhanced, and smoke taste was improved by adding the extracts; 3) the extract by supercritical fluid extraction was more suitable for cigarette flavoring.