Abstract: Granitic pegmatite-type Nb-Ta deposits are an important type of Nb-Ta deposit, primarily occurring in the Phanerozoic orogenic belts in China. In the Central Asian Orogenic Belt (CAOB), significant granitic pegmatite-type rare metal deposits, such as the Koktokay No. 3 vein, are well-developed but are mainly distributed in the western segment, with few reports from the eastern segment. The Majiagou Nb-Ta deposit in western Liaoning, recently discovered at the southeastern margin of the CAOB and the northern margin of the North China Craton, has an unclear metallogenic age and tectonic setting. This study investigates the granitic pegmatites of the deposit through petrology, geochronology, and geochemistry to determine the timing of granitic pegmatite formation and their petrogenesis. LA-ICP-MS U-Pb dating of columbite-group minerals reveals that the granitic pegmatites in the Majiagou area formed at 263.5±3.2 Ma, during the late Middle Permian, in a transitional setting between subduction and syn-collision. Geochemical analyses indicate that the granitic pegmatites are characterized by high Si, alkali, and Al contents, along with low Ca, Mg, Ti, and P contents, and are peraluminous. They exhibit extremely low total rare earth element (ΣREE=4.77×10^-6 to 15.94×10^-6) contents, narrow La_N/Yb_N ratios (2.11~9.70), and widely variable δEu values (0.51~3.31). The rocks are enriched in large ion lithophile elements (Rb, K, U, Sr) and depleted in high field strength elements (Nb, Ta, P, Zr, Ti), with low Nb/Ta ratios (average 6.8). These characteristics suggest that the magma underwent extensive fractional crystallization, and the pegmatites were formed through differentiation of granitic magma. The emplacement of granitic intrusions of different ages and the long-term complex orogenic evolution at the southeastern margin of the CAOB provided favorable geological conditions for the formation of highly fractionated pegmatitic magmas. This region holds significant potential for the exploration of pegmatite-type Nb-Ta deposits.