Abstract: An experimental study on process mineralogy, beneficiation and purification of ultra−large crystalline graphite ore from Aobao Mountain in Jiuquan, Gansu Province was carried out. The results showed that the graphite ore was fine flake crystalline graphite, the fixed carbon in the raw ore was 6.49%, the distribution rate of carbon−containing minerals in the graphite was 85.58%, the main gangue mineral was quartz, the content was 45.98%, followed by potassium feldspar and plagioclase, and the main metal minerals were pyrite and pyrrhotite. The distribution size of graphite mineral in the sample was mainly between 38 ~ 147 μm, and the process thickness was large, mainly 10 ~ 20 μm. Under the condition that the fineness of rough grinding was 60% −0.074 mm, the amount of rough collector kerosene was 90 g/t, the amount of foaming agent pine oil was 60 g/t, and the amount of water glass was 500 g/t, the closed−circuit flotation process of "one rough grinding, one rougher, two scavenging, six cleanings and seven re−grinding, and the middle ore is returned in sequence" was adopted. The concentrate product with fixed carbon grade of 98.01% and recovery rate of 99.22% could be obtained, and the product index reached the high carbon graphite standard, which could be used as the raw material of high performance materials such as expanded graphite. This study provided technical support for the high value utilization of graphite resources.