Abstract: Based on a comparative study of 90 abstracts of Papers 0n Ethnology，Demography and Anthropology，this paper investigates how the general rules of research paper abstracts work in these disciplines. The study indicates that discourse mode of most abstracts deviates from the traditional IMRD mode，showing a variety of characteristics. But they have in common in the use of modal verbs，voice and personal pronouns. This study also reflects that abstracts of Ethnology papers have more similarity to abstracts of Anthropology papers than those of Demography papers.

Key words: genre analysis, social science papers, English abstract, ethnology, demography, anthropology