Abstract: In this study, the essential oil of Ulva intestinalis was extracted by steam distillation (SD) and solvent extraction (SE). The chemical components of the two extracts were analyzed by GC-MS. The relative content of each component in each extract was determined by area normalization. The results indicate that the yield of SD extract (0.038%) was lower than that of the SE extract (0.800%). In the essential oil extracted by SD, totally 46 compounds were identified, accounting for 81.62% of the total detectable amounts. In the essential oil extracted by SE, totally 30 compounds were identified, accounting for 94.89% of the total detectable amounts. There were 21 compounds found in both of these two extracts, mainly including alkanes and aldehydes. In the SD extract the relative content of pentadecanal was the highest (18.12%), while in the SE extract the relative content of 8-heptadecene was the highest (51.49%).