Abstract: Six fossil teeth of Equus and Coelodonia antiquitatis from the Palaeolithic Site of Xujiayao were dated by uranium series method. The samples gave an internal concordant 230Th/234U age of about 100,000 years.
The measured 231Pa/235U ratios showed that these tooth samples were not of a closed system. Uranium had continuously been migrating in after fossilization. Nevertheless the 230Th/234U age can definitely serve as the upper limit of Xujiayao Site age.
The basic principle and technique of dating are described in the paper.

Key words: uranium series dating; Xujiayao Palaeolithic Site