Zircon U-Pb chronology, rock geochemistry and Sr-Nd isotope have been investigated in this paper to determine the formation time, genesis of rock and formation environment of the granodiorite in Shuangfengshan. The results show that the formation age of Shuangfengshan granodiorite is 334.8±2.1 Ma (MSWD=1.2). The rocks have relatively high SiO₂ (55.42%~65.53%), Na₂O+K₂O (7.42%~8.32%) and Al₂O₃ values (14.84%~17.53%), as well as K₂O/Na₂O ratios (0.16~0.29), which indicates that they are calc-alkaline, quasi-aluminum I-type granite. The rocks are rich in Rb, K, Nd, Zr and Hf, and relatively deficient in Nb, Ta, P, Sm and Ti. Nb/La (0.41~1.01) and Hf/Th (0.80~1.15) ratios are close to the data of typical island arc magmatic rocks. (⁸⁷Sr/⁸⁶Sr)_i(0.706 0~0.709 5) and εNd(t)(-0.22~+0.52) show characteristics of crust-mantle interaction. Combined with regional geological research, the authors hold that Shuangfengshan granodiorite originated from the basaltic lower crust formed in the late Mesoproterozoic on the active continental margin under the underplating of Early Carboniferous basaltic magma, which was the response of the northward subduction of the back-arc basin represented by the Huitongshan-Zhangfangshan ophiolite.