A series of granites crop out to the northeast of Erenhot City, near the China-Mongolian border. Zircon U-Pb dating and whole-rock elemental and Sr-Nd isotopic analysis were performed for four granitic plutons. The Halatumiao syenogranite intruded into the Middle-Devonian strata, showing geochemical features of aluminous to weakly peraluminous A-type granite, with A/CNK of 0.98~1.04, and its LA-ICP-MS zircon U-Pb age is 317.5±2.8 Ma (the Late Carboniferous). The Saiyinwusu, Yaguoaobao, and Gancihuduge plutons intruded into the Carboniferous strata, and their LA-ICP-MS zircon U-Pb ages range from 270.1±2.7 Ma to 273.8±1.6 Ma (the Early Permian). The Saiyinwusu pluton consists of biotite monzogranites, granodiorite, and syenogranite, while the Gancihuduge pluton is biotite monzogranites, and both plutons show transitional charac-teristics of I-and A-type granites. All the four granitic plutons are characterized by positive εNd(t) values ranging from +3.2 to +5.8 and variable I_Sr values from 0.703 58 to 0.709 92. Sr-Nd isotopic characteristics show that these granites are juvenile and thus are indicative of crustal growth. Combined with regional data, the study area probably have been subjected to an extensional setting during the Late Carboniferous to the Early Permian.