Abstract: ObjectiveThe Gejiu Tin Mine in Yunnan Province is one of the largest tin-polymetallic deposits in the world. The mineralization differences between the eastern and western regions are huge. The eastern region is characterized by the enrichment of super-large-scale tin-polymetallic deposits, while the mineralization scale in the western region is much smaller. MethodThis article takes the Baishachong rock body, Laoka rock body, and Masong rock body in the eastern region, as well as the Longchahe rock body and Shenxianshui rock body in the western region, as the research objects, and conducts systematic chronological and whole-rock geochemical comparative studies based on previous research results. Result The formation ages of granitic rocks in the eastern and western regions mainly range from 79.9 to 95 Ma, with similar characteristics of major elements and belonging to the same magmatic series. The distribution pattern of granite in the eastern region exhibits a "seagull-type" rare earth distribution curve, characterized by a depletion of light rare earths and an enrichment of heavy rare earths, with a strong negative Eu anomaly. It follows an approximate four-group effect distribution pattern, showing significant enrichment in incompatible elements such as Rb, Nb, Nd, Zr, and U. The distribution pattern of granites in the western region is characterized by a right-skewed REE distribution curve with light rare earth enrichment and heavy rare earth depletion, with small or insignificant negative Eu anomalies and significant enrichment in Th and Hf. Conclusion Compared to granites in the western region, granites in the eastern region have lower K/Rb, Zr/Hf, and Nb/Ta values and higher Rb/Sr ratios, indicating that granites in the eastern region have a higher degree of differentiation than those in the western region. The formation of highly differentiated magmas is the main cause of large-scale tin-polymetallic mineralization in the eastern region.