The Tianzhushan intrusive body is one of the representative plutons in the Dabie orogen, where late Mesozoic granitoid intrusive bodies are widely distributed, locates near the Wuhe-Shuihou fault which separates the UHP metamorphic complex of South Dabie from the block of North Dabie. This intrusive body is a composite intrusion consisting of three generations of intrusions: diorite, quartz syenite/granodiorite, and alkali-feldspar granite respectively from early to late. All the complexes belong to high-K calc-alkaline series, but the geochemical characteristics of the alkali-feldspar granite are remarkably different from other types of rocks and similar to things of A-type granite to a considerable degree. The alkali-feldspar granite has abundant enclaves and lower Zr saturation temperature,showing great difference from typical A-type granite and probably belonging to a highly evolved I-type granite. The geochemical characteristics of the Tianzhushan intrusive body are similar to those of other late Mesozoic granitoid intrusive bodies in the Dabie orogen, derived from partial melting of "old" lower crust under the tectonic backdrop of all eastern China lithospheric thinning in late Mesozoic. The granodiorite and alkali-feldspar granite are similar to each other in the emplacement age, and their zircon LA-ICP-MS U-Pb ages are 127.8 ±0.7 Ma and 127.7±1.0 Ma respectively, corresponding to the lithofacies features. It is thus held that the granodiorite had not been entirety concreted during the intrusion of the alkali-feldspar granitic magma.