Tin is an important strategic key metal and the study of its mineralization laws has valuable theoretical significance and economic value. Primary Sn mineralization is generally associated with highly evolved and relatively reduced granitic magmas. Compared with common granites, Sn-rich highly evolved granites often undergo complex evolution processes. We can’t obtain the early-stage magmatic compositions based on whole rock geochemistry analyses, which only represent the information of the last evolved samples, hindering our understanding of magmatic source and their evolution details. In addition, the explains for the whole rock analyses are not unique. Minerals crystallized in magma such as quartz, biotite, apatite can record the dynamic composition changes and fine evolution processes of magma that are difficult to reflect in whole rock analyses, showing unique advantages in the study of petrogenesis of granite. In this paper, we present a comprehensive major and trace element (including halogen) dataset for biotites from highly evolved granites in the Zengjialong Sn ore deposit. Biotites in the Zengjialong granite have a magmatic origin. They are characterized by low Mg# (5.70―9.93, mean = 7.63), high A/CNK values (1.77―1.98, mean = 1.88), similar to biotite compositions in S-type granites worldwide, suggesting the parental magmas were of meta-sedimentary origin. Biotite trace elements show that as the K/Rb ratios decrease, the Rb, Cs, and Sn increase and Pb decrease, indicating that the magma has experienced crystal fractionation dominated by K-feldspar. Tin contents in biotite increase by 4 times due to progressive fractional crystallization, indicating the Sn riched in the residual magmas. Biotites have low IV(F), IV(F/Cl), log(fHF/fHCl) and high IV(Cl) values, along with the negative relationships between IV(Cl) and IV(F/Cl), log(fH2O/fHF) and log(fHF/fHCl), suggesting the Zengjialong magma is F-rich and Cl-depleted magma system and the biotite crystallization process is accompanied by continuous fluid exsolution. The biotites in Zengjialong granite contains almost no Fe3+. In the Fe3+—Fe2+—Mg triangle diagram, the biotites are located below the FMQ line, indicating a low oxygen fugacity. The biotites in the Zengjialong granite record that the magma has an enriched source, high degree of differentiation, low oxygen, and continuous fluid exsolution. These processes are conducive to the tin enrichment and mineralization. Our study shows that biotite geochemistry data can be used to distinguish different magmatic-hydrothermal mineralization (Cu, Mo, W, and Sn) systems.