This paper is based upon the historical materials collected for the purpose of studying the problems of the clan, the family and the forms of marriage of the Hsiung-nu, a nomadic ethnic group in the northern borderland of ancient China. An attempt is made to analyze the relationship between the clan system and the political organization. The author finds that the external structure of the clans consists of a dual organization and the internal structure determines descent, succession, and inheritance of the clan members. In the section on marriage, he realizes that the moieties gradually lost their exogamous function as the Hsiung-nu came in frequent contact with the Han-Chinese. Forms of marriage, especially marriage by inheritance, are also discussed. A list of different types of families with estimated population is appended for the convenience of the reader to get a clear idea of the Hsiung-nu people in the Han Dynasty.