This study reports U-Pb isotopic geochronology and geochemistry of the Zhuxiling granodiorite plutons exposed in the northeast area of the middle-lower Yangtze area of SE China. We present convinced evidences of mechanism of the Mesozoic magmatism with petrochemistry, zircon U-Pb ages and Hf isotopes. The Zhuxiling granodiorites have high SiO2- and K2O-contents and low MgO-content, enriched in large ion lithosphere elements of K, Rb, Ba and Sr, low Sr/Y ratios, depleted in high field strength elements of Nb, Ta, Zr and Ti, significantly positive Pb-anomalies which showed a crust source. The Zr/Hf ratios of these granodiorites between 21.5 to 26.7 were dramatically lower than those of average crust which were around 35.5. It is speculated that the fractional crystallization of zircon may cause the decrease of Zr/Hf ratios in the melt. Analytical results of the zircon U-Pb dating yield an age of ca.140Ma for the formation time of Zhuxingling plutons and the zircon Hf isotope analysis showed that εHf（t） ranged from 2.3 to -4.76 which only few was above the 0. Taken the background of the study area and the SE China into consideration, we came to a conclusion that the theses plutons in Zhuxingling maybe formed in an extension back-arc setting which is related to the Pacific plate subduction.