In order to study the diagenesis and mineralization mechanism of Jinjiling Pluton and pegmatite in western section of Nanling Mountains. Through analyzing the variation of biotite chemical component to trace magma evolution, reflect magmatic crystallization conditions and provide important information for mineralization enrichment mechanisms. And further exploration relationship between magmatic evolution and mineralization of Jinjiling pluton.Methods:Combined with field work and microscope observation,using EPMA and LA- ICP- MS analysis to determine major and trace element compositions of the biotite respectively in the Jinjiling Pluton and pegmatite.Results:The mica in the Jinjing Pluton (syenogranite, biotite pegmatite, greisen and quartz veins) are similar in chemical composition, rich in FeO, Al2O3, F and Li2O*, and poor in MgO, CaO, Na2O and MnO, all belonging to Li—Fe mica. The content of SiO2 (~ 34.06% ~ 34.01% ~ 43.31%), Al2O3(~ 12.91% ~ 15.99% ~ 22.30%) and H2O* (~ 1.54% ~ 1.78% ~ 2.00%) in mica increased significantly from syenogranite to pegmatite and then to dolomite and quartz veins. The content of FeOT(~ 31.80% ~ 30.42% ~ 16.02%), MgO(~ 2.23% ~ 1.03% ~ 0.66%) and TiO2 (~ 2.72% ~ 2.07%~ 0.11%) decreased significantly.The trace elements of biotite in the Jinjiling Pluton and pegmatite show the same variation trend on the trace element spider and the REE partition diagram, showing the flat partition pattern of rare earth elements, accompanied by obvious negative Ce and Eu anomalies.The rare earth element content of biotite in pegmatite (mean 154 μg/g) is significantly higher than that in rock mass (mean 28.7 μg/g). Biotite in pluton and pegmatite is rich in Rb, Nb, Ta, Pb, Nd, Sm and poor in Th, Ce, Sr, Zr and the average content of Rb, Li, Be, Nb and Ta shows an increasing trend from rock mass to pegmatite: 2016 2824 μg/g, 620 2135 μg/g, 2.50 9.13 μg/g, 362 716 μg/g, 30.4 44.6 μg/g, while that of the average content of Ba decreased (189 to 126 μg/g).Conclusions: The Jinjiiling porphyritic- like syenogranite originated from the proterozoic crust, it has similar mineral composition with the biotite granite—pegmatite. The biotite in the two types of rocks shows a transition relationship from siderophylite to protolithionite to zinnwaldite, and the chemical composition shows a good relationship between affinity and evolution. It is the product of different stages in the continuous crystallization differentiation of homologous magma.Jinjiling pegmatite is a highly evolved rock type, formed during the magmatic—hydrothermal transformation stage, which is a special product between granite and greisen, and the pegmatite stage is an important stage for the enrichment of rare metal elements, especially Sn, and even further mineralization.