Abstract: This study conducted analysis on the Pingshi granitic pluton in the Hengshiarea, southern Jiangxi Province using LA-ICP-MS zircon U-Pb dating, petrologicaland geochemical methods. The results show that the zircon U-Pb ages of thebiotite monzogranite in the studied areas are 456.1±3.8 Ma and 441.3±5.2 Ma, indicating the Pingshi granitic pluton formed in Late Ordovician to Early Silurian. Geochemical result shows that the Pingshi granitic pluton has ACNK of 1.1～1.29 and K₂O/Na₂O of 0.97～1.51, suggesting that they belong to peraluminous and high-K calc-alkaline rock. The pluton has a total REE content of(113～250)×10^-6, and is enriched in LREE, with distinct right oblique REE patterns, Eu valuesof 0.38 to 0.67 and obvious negative Eu anomaly. The REE analysis shows the pluton is enriched in Rb, Th+U, La+Ce, Nd and Zr+Hf+Sm, and depleted in Ba, Nb, Srand Ti, with Rb/Sr ratio of 0.60～2.82(averaging 1.66)obviously higher than the average values of continental crust and the upper crust, suggesting that the pluton is of the characteristics of crust derived granite. The Pingshi granite pluton might result from the Caledonian movement of late Early Paleozoic, and broke up after collision matching between Cathaysian block and Yangtze block. S-typegranitic magmas, formed by partial melting of the upper crust in the period ofMiddle Ordovician to Silurian, ascended to the shallow part of the crust and yielded the Pingshi granite pluton in the period of collision to post-collision.