Xiaotuergen is the first porphyry copper deposit discovered in Nuoerte area in recent years. Granite porphyry, granodiorite porphyry and biotite monzonitic granite are widely developed in the ore district, and the mineralization is closely related to the granodiorite porphyry. In order to investigate the petrogenesis of intrusive rocks and their intrinsic relationship with copper mineralization, the authors carried out the petrographic and geochemical studies of the widely developed intrusive rocks in the ore district. The results show that all rocks exhibit high silica and alkaline, with moderate aluminum content. They belong to high-K calc-alkaline and shoshonitic rocks. All samples are enriched in Rb, Ba and other large ion lithophile elements(LILE) and LREE, and relatively depleted in Nb, Ta, Ti, P, Sr and HREE, indicating that they were formed by comagmatic differentiation and evolution in a continental arc environment. Combined with regional geological background, the authors hold that these rocks are the product of subducted oceanic crust which experienced partial melting, replacement of overlying mantle wedge and fractional crystallization during the rising process. A comparison with the formation conditions of typical reduced porphyry copper deposits shows that the Xiaotuergen ore district has the potential to form porphyry deposit.