Abstract: Late Carboniferous granites are widely exposed in the Huren mutumen Woblezhuo area, Sonid Left Banner, Inner Mongolia. LA-MC-ICPMS U-Pb dating of zircons from magmatic rocks shows that the intrusion ages of biotite-bearing monzonitic granites are(317.0 ± 1.6) Ma and (313.5 ± 1.5) Ma in the study area。This suggests that the rocks studied in this paper were formed in the Bashkirian-Moscovian(Pennsylvanian). By the geochemical analysis, the samples are peraluminous high-K calc alkaline series rocks. In the chondrite-normalized REE diagrams, it exhibits ΣREE content ranging from 110.77 × 10^-6 to 147.29 × 10^-6, enrichment in LILE and LREE, depletion in HREE and HFSE. In the primary mantle-normalized trace element fractional diagrams, it shows that the major lithophile elements such as Rb, Th and U are relatively enriched, while the high field strength elements such as Nb, Ta, HF and Zr are slightly enriched, and Ba, Sr and Ti are relatively depleted. the paleo-asian ocean closed before the Late Carboniferous epoch, and the biotite-bearing monzonitic granites developed in a post-orogenic extensional regime in the study area.