Abstract: The Kangding complex that is extensively distributed in the Kangdian Axis on the western margin of Yangtze Platform is greatly disputed in terms of its formation age. In this paper, migmatite in Datian region which has rarely been referred to before was selected to perform U-Pb zircon LA-ICP-MS age determination. The results show that the ages are mainly concentrated from 744Ma to 772Ma, suggesting that the complex was formed in Jinning orogeny period; moreover, this conforms to the zircon dating results specific to the Kangding complex presented by other researchers, which further indicates that the strongest migmatization event of Xikang-Yunnan Axis occurred in the Jinning period. There exist two distinctly different REE patterns of the migmatite which indicates geochemical characteristics of anatexite. At the early stage of anatexis, the magmatite produced positive anomaly of Eu; whereas at the later stage, Eu negative anomaly implying a process of differentiation crystallization was produced. The beneficial host rock of uranium mineralization is the magmatite formed by differentiation crystallization in the late period of anatexis.