Abstract: The Nanwenhe tungsten deposit is the largest scheelite deposit in southeast Yunnan. Since the Caledonian period, the area has been subjected to multi−stage tectonic−metamorphism. This has led to different understanding of key issues such as deposit genesis and metallogenic age. On the basis of detailed field geological work, combined with the results of previous work, it is considered to be a skarn scheelite deposit controlled by magmatic−hydrothermal fluid, and the ore−forming fluid is a magmatic−hydrothermal transitional fluid, which is characterized by " cross−bedding" and " bedding" quartz veins−feldspar quartz veins, and controls the skarnization and scheelite mineralisation of the Nanwenhe tungsten deposit. The laminated and stratiform skarn ore bodies revealed by the current exploration work are the products of bedding metasomatism of "mag~hydrothermal transition ore−forming fluid". The Sm−Nd isotopic dating of the scheelite in the Nanwenhe tungsten deposit yield a metallogenic age of 126±6.7 Ma (n=7, MSWD=0.33), which corroborates well with the tectonic research results and other chronological results in the area, indicating that the mineralization is related to the late Yanshan magmatic activity. The geological characteristics and Sm−Nd isotopic age of the deposit indicate that the Nanwenhe tungsten deposit is a skarn scheelite deposit controlled by the late Yanshanian magmatic−hydrothermal system.