Abstract: There is little report on the Early Paleozoic magmatic events in the Jitang area, eastern Tibet.The Middle-Late Ordovician granites have been discovered in Langla Mountain, Jitang.The weighted average U-Pb age of the granite is 455±2.0 Ma(WSWD=1.15, n=26) by the LA-ICP-MS U-Pb dating of the zircon, indicating that it was emplaced in Middle-Late Ordovician.The geochemical characteristics indicate that the granite has high SiO₂(78.72%~79.48%), high potassium(K₂O/Na₂O=5.55~10.20), low MgO(0.10%~0.25%), with aluminum supersaturated index A/CNK values ranging from 1.08 to 1.26, and the rock is a high-potassium-calcium- alkali-strong over aluminum S-type granite.The REE contents of rocks are enriched in LREE and depleted in HREE, with a negative Eu anomaly and δEu values ranging from 0.35 to 0.39.They are also enriched in LILEs (Rb, Th, Nd and Pb), but depleted in HFSEs (Ba, Nb, Sr, P and Ti).Combined with regional geological data, it is suggested that the granites might have originated from partial melting of ancient crustal materials, caused by the subduction of the Proto-Tethys, and is the response of the magmatic events during subduction of the Proto-Tethys.