Abstract: The West Kunlun Orogenic Belt of the 509 Daobaxi deposit is a super-large Li-Be rare metal discovered in recent years. In order to study the magmatic differentiation and evolution process of granite pegmatites in the mining area, and establish the mineralogical indexes of each stage of magmatic evolution and rare metal mineralization, this paper used electron probe in-situ principal element analysis and automatic mineral analysis system (TIMA) to study various types of garnet in the mining area.The results show that the garnet in the granite-pegmatite in the mining area is of magmatic origin, belonging to the almandine-spessartine solid-solution, and the garnet in the metamorphic sandstone is of metamorphic origin.The garnet in the area is gradually enriched with the deepening of magma evolution. High-Mn garnet (MnO＞22.5%) can serve as a marker for highly differentiated mineralised pegmatites in the region.Due to tourmaline crystal differentiation, Mn content increases and Fe content decreases from core to edge of pomegranate.The evolutionary sequence of pegmatite is Muscovite granite-pegmatite, Muscovite tourmaline granite-pegmatite and ore-bearing pegmatite.