Mabja lagre leucogranitic pluton emplaced at the southwestern of North Himalaya Sakya dome during the Late Miocene period and located at the footwall of Xainza-Dinggye S-N normal fault. The 10Ma Mabja leucogranite have homogeneous elements and isotopic (Sr and Nd) compositions, however, obviously different from the great of Himalaya leucogranites, it is show relatively unradiogenic Sr (87Sr/86Sr(i)=0.85033~0.85034) and Nd (εNd(i)=-19.26~-18.30) isotope compositions, indicate that the Mabja leucogranite may be resulting from anatexis of much more mature crust materials. The SHRIMP zircon U-Pb dating results of the Mabja leucogranite show: (1)This pluton records at least two stage magmatic crystallization, happened at 11.6±0.2 Ma and 9.6±0.2 Ma respectively; (2) A few 13.8~16.0 Ma magmatic crystallized zircon ages; (3) most of the inherited zircon core ages are distributed to Pan-Africa period, whereas exists a few Paleoproterozoic ages (1558~1584 Ma). 40 km ward the south, a suit of Paleoproterozoic mylonites distribute at the Ama Drime Massif, which also located at the footwall of Xainza-Dinggye normal fault. The elemental compositions of these mylonites are quite like meta-pelites of High Himalaya Crystalline Sequence, show high SiO2 (70.6%~74.6%), Al2O3 (12.3%~14.0%), K2O (4.22%~4.93%), A/CNK (1.50~1.58) and K2O/Na2O (1.42~2.18), represent the major anatexis mature crust materials that forming Mabja leogranitic pluton. Related to the E-W extension along the southern Tibetan rift system, a Late Miocene event of anatexis took place in North Himalaya region. The mixing source of meta-pelites and mature crust materials began to be melting at 16.0 Ma, reached its anatexis peak between 11.6 Ma to 9.6 Ma, and then drawing up along the S-N normal fault, emplaced in the Tethy Himalaya sequence and formed the Late Miocene leucogranitic plutons.