The Yangmingshan Tashan batholith, located at the junction of the Yangtze and Cathysia blocks, is mainly composed of monzonitic granites with different granularity and phenocryst content. In this article, a research combined of LA-MC-ICP-MS zircon U-Pb chronology, geochemistry and Sr Nd isotopes on several samples of different lithologies of granitoid is reported to constraint its petrogenesis and tectonic setting. The result shows three granitic samples of different granularity from the Tashan bathoilth yield ages from 2134~2215 Ma, while one sample from Yangmingshan batholith yields a age of 213.7±1.0Ma, both of them belong to late Indosinian. Geochemically these samples are relatively enriched in SiO2 (70.43%~74.06%) and Al2O.3(A/CNK=1.03~1.24) that can be easily identified as peraluminous series. Further discrimination indicates metagraywackes are the dominate source materials to the Tashan batholith, and metapelites to the Yangmingshan batholith. High Rb、Th、U、Ta abundances and strong depletion of Ba, Sr, Nb, Ti, Eu, elements indicates they experience high fractionation process. High (86Sr/87Sr)i ratios (0.72993~0.77391) and low εNd(t) values (-99~-1211) with tDM2(Nd) of 1801~1978Ma reveal that their sources have involved in the crustal cycle for a long time. Intergrated with Indosinian tectonic involvement of South China, partial melting of thickened middle crust under local extension thinning mechanism may be the key factor controlling the granitic intrusionism of the Tashan Yangmingshan region. 3523 Ma inherited core of one zircon show that ancient Archaeozoic basement did exist in this region.