Abstract: Whether in tribal societies or in great empires of ancient civilization, exogamous alliance is always important means to strengthen the statues o f a social group .Taking the eminent Gao-jia clan as a case, this article discusses the issue of cross-group marriage among the famous lineages belonged to the Imperial Household Department .The authors make a textual research to the official records, in comparing with rare edition copies of Genealogy of Gao-jia Clan , put in order the historical facts concerning to this descent group, and then intricate the complex kinship relations both in written text and in anthropological diagrams.