Abstract: The Shi-Hang belt is an important magmatic zone composed of granites with relative higher εNd(t) values and younger tDM model ages and trends NNE. The granites in Southern Hunan and Northern Guangxi include the Qianlishan, the Qitianling,the Xishan, the Jinjiling, the Huashan and the Guposhan granites. Recently a series of zircon SHRIMP U-Pb ages indicate that all these granites were emplaced in a narrow time interval of 151~163 Ma. However, ages of granites decrease from the southwest to the northeast. These granites have similar geochemical characters. All of them are enriched in alkalies and potassium, and have high contents of LILE and HFSE. In geochemical discriminating plots, these granites fall in A-type granite field. Thus, the Southern Hunan-Northern Guangxi granite belt belongs to an A-type granite belt. These granites are further classified to A2 type.These granites have relatively lower (87Sr/86Sr)i values, higher εNd(t) values and younger t DM model ages. From the southwest to the northeast, εNd(t) values gradually decrease. Abundant mafic microgranular enclaves were found in most granites. Petrogeology and geochemistry, especially Hf isotopes of zircon from the MMEs and host rocks indicated that these granites formed by crust-mantle magma mixing processes. The mantle-derived magma end-member came from depleted mantle, and might be directly related with the asthenospheric mantle. The A-type granite belt might form at back-arc or intra-arc extension environment triggered by subduction of palaeo-Pacific plate. The strong mantle-crust interaction caused by upwelling and underplating of the asthenospheric mantle across the trans-crustal faults is the major mechanism for generating the A-type granites in the belt. The extension and thinning of the continental crust began from the southwest to the northeast, and the intensity of extension decreased from the southwest to the northeast. The Shi-Hang South Belt is an important W-Sn mineralization belt. All these granites belong to Sn-rich granite. Mechanism of tin concentration in these granites is different with common tin granites, in which tin is concentrated by fractional crystallization. Tin mineralization models are abundant in the belt. Different with traditional tin mineralization model,tin mineralization in the Furong tin deposit was related with chloritization of granites by later meteoric water hydrothermal system.Studies on these granites and related tin mineralization may enrich mineralization theories of A-type granites.