The formation of Mesozoic mafic dykes in South China is usually related to intraplate extensional activities. They are not only probes for deep mantle evolution, but also tools for studying geodynamic background. In this paper, high- precision LA- ICP- MS zircon U- Pb isotope dating, whole- rock major and trace element and Sr- Nd isotope and mineral chemistry analyses were conducted for the Jinjiling diabasic dikes, southern Hunan province, to explore the relationship between their petrogenesis and the evolution of the lithospheric mantle and the geodynamic background of the inland area of South China. The results show that the zircon U- Pb age of the Jinjiling diabasic dikes is 153. 1±1. 0 Ma, suggesting that they are the product of late Jurassic magmatism. They are enriched in light rare earth elements (LREEs), large ion lithophile elements (LILEs) and high field strength elements (HFSEs), without Nb and Ta negative anomalies, showing the typical ocean island basalt (OIB)- like geochemical affinity. These characteristics show that the magma source is independent from the island arc environment, and less crustal contamination. The initial 87 Sr/86 Sr ratio of 0. 7062 to 0. 7080 and εNd( t ) of +1. 76 to +3. 75 are also consistent with the characteristic of OIB mantle source. The study shows that the Jinjiling diabasic dikes should be derived from partial melting of the lithosphere mantle which was eroded/metasomatized by the asthenosphere originated melts, and the magma underwent fractional crystallization and slight crustal contamination in the emplacement process. Those magmatic rocks are the response of mantle alteration/lithospheric thinning and the reflection of asthenosphere- lithosphere interaction. The Mesozoic magmatism in the inland area of South China may have no relation with the subduction of the paleo- Pacific plate, but be the product of the asthenosphere upwelling and lithosphere thinning under the background of the intracontinental rift.