Abstract:A series of granitoids are distributed in the western margin of the Yangtze Block from late Mesoproterozoic to middle Neoproterozoic, which is an important window to explore the convergence and disintegration of the Rodinia supercontinent. The Huangcaoba granitoid pluton, which consists of gneissic granite, monzonitic granite and biotite granite, is located in Xujie area of Mouding County, Yunnan Province of the western margin of the Yangtze Block. The granites have the characteristics of high silicon (SiO2 70.77% ~ 78.79%), high alkali (Na2O + K2O) (7.15% ~ 8.73%), high ratio of FeOT/ (FeOT + MgO) (0.70 ~ 0.98) and 10000 × Ga/Al (2.68 ~ 6.84), low calcium (CaO 0.07% ~ 0.90%), and low magnesium (MgO 0.02% ~ 0.88%) in terms of main element composition. In terms of REE composition, the LREE is relatively enriched and has obvious negative Eu anomaly characteristics. In terms of trace elements, Rb, Th, U, K, Nd, and Sm are relatively enriched, Nb, Zr, Hf are relatively depleted, and Ba, Sr, P, Ti are strongly depleted. The characteristics of main element and trace elements indicate that the Huangcaoba A- type granitoid pluton belong to A- type granite. In situ U- Pb dating of zircon shows that the gneissic granite (1090 ± 24 Ma) and monzonite granite (1063 ± 5 Ma) were both formed in the Middle Proterozoic era, εHf(t) = +4.3 ~ +10.3, TDM2 age is 1.33 ~ 1.62Ga, indicating that the diagenetic material comes from the partial melting of the new crust. The crystallization age of biotite granites is 782.4 ± 8.2 Ma (ICP- MA U- Pb method), belonging to the Neoproterozoic era, with εHf(t)= -7.3 ~ -2.1, which all fall below the chondrite evolution line. The TDM2 age is between 1.80 ~ 2.14 Ga, indicating that the ore- forming materials are more likely to come from the ancient crust. Based on the analysis of previous research data, the paper holds that the Huangcaoba A- type granitoid pluton was originated in post orogenic extension environment during the multi- stage orogenic cycle in the Mesoproterozoic to Neoproterozoic period.