The Shazaoyuan composite pluton consists of 4 intrusive granitic rocks in the southern Beishan Mountains, which include medium to fine grained biotite granodiorite, fine grained biotite quartz diorite, medium grained biotite monzonite granite, and medium to coarse grained biotite syenogranite. Zircon LA- ICP- MS U- Pb dating result shows that medium to fine grained biotite granodiorite, fine grained biotite quartz diorite and medium grained biotite monzonite granite intrusion occurred in the Late Permian (252. 1±1. 9 Ma, 252. 2±2. 1 Ma and 248. 8±3. 5 Ma), and is the product of the Late Hercynian Period. However, medium to coarse grained biotite syenogranite intrusion occurred in the Early Triassic (246. 4±2. 0 Ma), and is the product of the Early Indosinian Period. Geochemically, they are all characterized by the chondrite- normalised REE distribution pattern displaying right skewed shapes, distinct fractionation between LREE and HREE, are enriched in light rare earth elements and depleted in heavy rare earthelements. In addition, medium to fine grained biotite granodiorite and fine grained biotite quartz diorite are characterized by high content of SiO 2, Al 2O 3 and Na 2O, low content of MgO, are strongly enriched in Sr and depleted in Y and Yb, with unobvious Eu anomalies (δEu=0. 75~1. 16) that are similar to the typical adakites. However, medium grained biotite monzonite granite and medium to coarse grained biotite syenogranite are characterized by high content of SiO 2, K 2O, and K 2O+Na 2O, modertate content of Al 2O 3, with negative Eu anomalies (δEu=0. 45~0. 73) and strongly negative Eu anomalies (δEu=0. 02~0. 08) respectively. The geochronological and geochemical features of the Shazaoyuan granitic pluton indicate: ① medium to fine grained biotite granodiorite and fine grained biotite quartz diorite belong to peraluminous- weakly metaluminous calc- alkaline I- type granites with typical adakite characteristics, medium grained biotite monzonite granite belongs to weakly metaluminous and high K calc- alkaline I- type granite, but medium to coarse grained biotite syenogranite belongs to weakly metaluminous and high K calc- alkaline A2 type granite; and ② the magmas of medium to fine grained biotite granodiorite, fine grained biotite quartz diorite and medium grained biotite monzonite granite were probably derived from partial melting of the lower crust basaltic rocks, and contaminated by the lower crust materials during magma intrusion, whereas the magmas of medium to coarse grained biotite syenogranite were derived from partial melting of the juvenile crust rich in biotite pelitic source; and ③ medium to fine grained biotite granodiorite, fine grained biotite quartz diorite and medium grained biotite monzonite granite were the outcome of emplaced magmas in the subduction- collisional tectonic setting, but medium to coarse grained biotite syenogranite was the outcome of emplaced magmas in the syn- collisional and post- collisional tectonic setting.