Highly fractionated granite has received widespread attention due to its unique mineralization specificity. The Meibaqieqin complex rock mass in Xietongmen County is exposed in the Gangdise metallogenic belt, composed of biotite syenogranite, two-mica syenogranite, and muscovite syenogranite,with tungsten-tin ore body occurring within the muscovite syenogranite mass or its marginal zone. Through detailed geological investigations, LA-ICP-MS dating revealed weighted average 206Pb/238U ages of 129.7±0.9 Ma (biotite syenogranite), 128.4±1.6 Ma (two-mica syenogranite), and 129.5±0.5 Ma (muscovite syenogranite). The granites exhibit high SiO2, K2O, and K2O+Na2O contents, and low Al2O3, CaO, and MgO contents. They are relatively enriched in elements such as Zr, Nb, Ce, Y, and Hf, while depleted in Ti, Ba, Sr, and P. The granites display high 10000Ga/Al values, Zr saturation temperatures, and distinct Eu negative anomaly, indicating their characteristics as highly differentiated A-type granites formed in a post-collisional extensional setting. The muscovite syenogranite is the final product of differentiation, representing a rare metal granite with evident four-group fractionation effects of rare earth elements. Intense melt-fluid interaction further enriched rare metals such as W, Sn, Nb, and Ta, while the post-collisional extensional setting and thermal disturbance not only provided pathways and heat sources but also prolonged the magma differentiation, favoring the formation of large to super-large rare metal deposits with high grades. The Meibaqieqin area possesses favorable metallogenic geological conditions, suggesting its potential for generating large to super-large deposits. this study provides important guidance and reference for the exploration of rare metals such as W, Sn, Nb, and Ta in the Gangdise metallogenic belt.