Objectives:The giant grained uraninite found in Muding area, Yunnan Province, is very rare in the world and there is a very special “uraninite—rutile(mass)—zircon(small amount)” mineral assemblage. The genesis of uranium mineralization and the formation mechanism of the giant grained uraninite like puzzles have plagued the uranium geologists for many years. Methods:In recent years, we have carried out comprehensive studies，including petrology, mineralogy, petrogeochemistry, isotopic geology and chronology. Results:It is confirmed that the uranium- riched rock is albitite, which mainly composed of albite(average An=3.36).The average Na2O content of the albitite is 10% and belongs to alkaline and strong peraluminous rock. albitite has characteristics of high DI (average is 82.39%) , high FL(average is 88.39%) , high FM(average is 84.92%) , low SI(average is 5.06%) and very low ∑REE content(average∑REE is 162). The \[n(87Sr)/n(86Sr)\]iof albitite＞0.710; zircon age of albitite（SIMS） is 1057 Ma, close to the age of Shuiqiaosi rock(1038~1070 Ma). The REE patterns of uraninite are consistent with magmatic uranium deposits ,which is formed in high temperature geological environment(about 662.19℃). Conclusions:Albitite is the farthest product of Shuiqiaosi highly fractionated rock from biotite microcline granite— biotite microcline albite granite— albite granite— albitite. The uraninite and albitite have the characteristics of homology, Co- evolution and close to simultaneous formation, and then confirm the uranium mineralization in the Muding area is a new type relation to albitite and has the genesis characteristics of rock fractionation. Ti plays a crucial role in the U complexation, migration and formation of giant grained uraninite. In addition,in the process of evolution and fractionation of Shuiqiaosi rock ,not only the occurrence of uranium mineralization is controlled, but also the occurrence of Nb and Ta mineralization in the stage of albite granite.