Abstract: In recent years, with deep-going mineral exploration and discovery of a number of important copper-polymetallic mineral deposits, the Sino-Mongolia border region has become one of the hot areas for exploration of copper, gold and other metals in the world early in this century. The discovery and exploration of the Ouyu Tolgoi porphyry Cu-Au deposit is the best example. An intensive analysis and study of the tectonic setting of the deposit and a good knowledge of the geological and petrological characteristics of the deposit has guiding significance for raising the level of mineral exploration on the Chinese side of the Sino-Mongolia border region.