Located in the eastern Central Asian orogenic belt, Ar Horqin area has widely distributed Mesozoic magmatic rocks. In this paper, petrologic and element geochemical studies were carried out for the early Cretaceous intrusive rocks in Ar Horqin area. The study of petrology indicates that the granitoids are mainly composed of granodiorite, adamellite and granite-porphyry. Major element geochemistry shows that the rocks are quasi-aluminous cal-alkaline granites, which are characterized by relatively rich silicon and sodium and poor potassium. Trace elements have a similar variation trend characterized by low REE, fractionation of REE, significant negative anomaly of Eu, depletion of Nb, Ta, P, Ti, and enrichment of LREE, Rb, Th, U, Zr, La. Main body of the granites belongs to calc-alkaline I genetic type. The magmas were formed by partial melting of the crust in an extensional setting after the collision, which was a favorable metallogenic tectonic evolution stage. DI values, K/Rb and Rb/Sr ratios are larger, SI values are smaller, and Fe₂O₃/FeO ratios are also larger, suggesting that the granites belong to low evolution, highly fractionated oxidation type or magnetite series. Their geochemical ore parameters indicate that Mo, Cu, Pb-Zn mineralization potentiality decreases systematically, and Au mineralization potentiality is poorer.