The lipid content is a critical criterion for the evaluation whether the microalga was qualified as biofuel material. In the present study, the crude lipid of seven species of marine microalgae was extracted by ethyl ether using Soxhlet extraction method, under a temperature of approximately 60-80 ℃. The Soxhlet extraction method was improved by dipping the microalgae in ethyl ether for some time before leaching. The results show that the lipid contents were higher than 15% for the seven species of marine microalgae. The lipid contents of Nannochloropsis Oculata, Isochrysis zhanjiangensis and Chaetoceros muelleriwere are higher than 25%. Variation of the results acquired by the traditional method and the improved method was less than 3.5%, which indicated that there was no significant difference. Moreover, the crude lipid was extracted more thoroughly by the improved method, within a much shorter time. In conclusion, the improved Soxhlet extraction was more efficient, with lower cost and more thorough extraction. What’s more, the pollution caused by ethyl ether was reduced due to a shorter extraction time.