As one of the most important Pb-Zn ore concentration areas in China, southern Hunan-northern Guangdong area is located in the middle part of the Nanling metallogenic belt. Morphology, texture, composition, δ³⁴S and composition of fluid inclusions of sphalerite from MVT and magmatic hydrothermal Pb-Zn deposits were investigated to discuss the ore-forming temperature, the source of sulfur and the ore-forming fluid, which can provide valid constraints on the mineralization. It is suggested that lead-zinc sulfides in the MVT Pb-Zn deposit were formed in the medium-low temperature, oxidative-weak reductive and lower stress environment. The sulfur was mainly derived from the ore-bearing strata, the ore-forming fluid was composed of hot brine and metamorphic dehydration of the sediments. Magmatic hydrothermal Pb-Zn deposits were formed under the medium-high temperature, weak reductive and higher stress condition. The sulfur was mainly derived from the magma, the ore-forming fluid was composed of magmatic hydrothermal solution in the early stage and mixed fluid in the late stage. Based on the formation time, spatial distribution and tectonic background of the orebodies and the rocks, it is held that magmatic hydrothermal Pb-Zn deposits were formed by the emplacement of the large-scale granitic magmatite which was caused by subduction of the Paleo-Pacific plate to the mainland, thus the lithosphere was thickened in the Early Yanshanian period (180~150 Ma), and that MVT Pb-Zn deposits were formed after the superimposed reformation of the original Devonian source bed by the magmatic hydrothermal solution formed by the Eurasian lithospheric extension-thinning in the Late Yanshanian period (130~90 Ma).