The Kejie pluton is located in the north of the Changning-Menglian suture zone. The rock types are mainly biotite-granite. Zircon LA-ICP-MS U-Pb dating indicates that the Kejie pluton emplaced at about 80–77 Ma, Late Cretaceous. The Kejie pluton samples are characterized by high SiO2(71.68%–72.47%), K2O(4.73%–5.54%), total alkali(K2O + Na2O = 8.21%–8.53%), K2O/Na2O ratios(1.36–1.94) and low P2O5(0.13%–0.17%), with A/CNK of 1.025–1.055; enriched in U, Th, and K, depleted in Ba, Nb, Sr, Ti, P and Eu. They are highly fractionated, slightly peraluminous I-type granite. The two samples of the Kejie pluton give a large variation of εHf(t) values(-5.04 to 1.96) and Hf isotope crustal model ages of 1.16–1.5 Ga. Zircon Hf isotopes and zircon saturation temperatures of whole-rock(801°C–823°C) show that the mantle-derived materials maybe have played a vital role in the generation of the Kejie pluton. The Kejie pluton was most likely generated in a setting associated with the eastward subduction of the neo-Tethys ocean, where intrusion of mantle wedge basaltic magmas in the crust caused the anatexis of the latter, forming hybrid melts, which subsequently experienced high-degree fractional crystallization. The Kejie pluton is located in the north of the Changning-Menglian suture zone. The rock types are mainly biotite-granite. Zircon LA-ICP-MS U-Pb dating indicates that the Kejie pluton emplaced at about 80-77 Ma, Late Cretaceous The Kejie pluton samples were characterized by high SiO2 (71.68% -72.47%), K2O (4.73% -5.54%), total alkali (K2O + Na2O = 8.21% -8.53% and low P2O5 (0.13% -0.17%), with A / CNK of 1.025-1.055; enriched in U, Th, and K, depleted in Ba, Nb, Sr, Ti, P and Eu. They are highly fractionated, slightly peraluminous I-type granite. The two samples of the Kejie pluton give a large variation of εHf (t) values ​​(-5.04 to 1.96) and Hf isotope crustal model ages of 1.16-1.5 Ga. Zircon Hf isotopes and zircon saturation temperatures of whole- rock (801 ° C-823 ° C) show that the mantle-derived materials maybe have played a vital role in the generation of the Kejie pluton. The Kejie pluton was most likely generated in a setting associated with the eastward subduction of the neo-Tethys ocean, where intrusion of mantle wedge basaltic magmas in the crust caused the anatexis of the latter, forming hybrid melts, which presents experienced high-degree fractional crystallization.