The deep process is an ultimate restrictive factor for Mesozoic largescale petrogenesis and mineralization in Hunan and Jiangxi Provinces. Mesozoic polymetallic ore deposits in HunanJiangxi Provinces is an important component of metallogenic belt of the Pacific Rim, the ultimate constraints of Mesozoic largescale mineralization in the area from the deep Earth. Lithosphere structure is an important part of the deep Earth, and the lithosphere thickness is another important parameter of the lithospheric structure. Using the mantle melting column（Langmuir et al, 1992） model estimated the forming depth of basic rocks. By the Changchengling basalt and northwestern Jiangxi mafic rocks, using main elements of basalt, we make the depth quantitative simulation of depth of basalt formation, and study evolution of lithospheric thickness preliminary in HunanJiangxi Province. Combined with the previous geochronology, geochemistry and isotopic information, we can indicate that the lithosphere thickness is about 53 km in Southwest Hunan province of Late Triassic and 81～84 km in South Central Hunan province of Late Triassic and 60～63 km in Northwest Jiangxi province of Early Cretaceous.