Multistage　magmatic　thermal　events　occurred　in　the　Yardoi　Dome　and　contain　important　information　on　the　tectonomagmatic　processes.　The　dome　has　played　a　crucial　role　in　understanding　the　collisional　evolution　of　the　Tethyan　Himalayan.　We　present　new　geochronological　and　geochemical　data　for　muscovite-granite　exposed　in　the　Liemai　area,　Eastern　Tethyan　Himalayan　Belt.　Liemai　muscovite-granite　is　strongly　peraluminous,　with　A/CNK　values　characterized　by　evolved　geochemical　composition　with　high　contents　of　SiO2-enriched　large-ion　lithophile　elements,　and　is　depleted　of　high-field-strength　elements.　These　geochemical　features　indicate　that　granites　possibly　derived　from　partial　melting　of　metasedimentary　rocks　and　plagioclase　fractional　crystallization　probably　played　a　critical　role　in　production　of　peraluminous　granitic　melts.　Zircon　U-Pb　dating　from　muscovite-granite　yielded　ages　of　approximately　48.5　+/-　1.1　Ma,　representing　its　crystallization　ages.　This　age　is　the　oldest　age　of　Tethyan　Himalayan　leucogranite　from　the　Yardoi　Dome　and　adjacent　areas.　However,　the　inherited　zircon　cores　have　ages　of　135.7-3339.2　Ma.　The　epsilon　Hf(t)　values　of　all　zircons　vary　from　-6.4　to　-2.3　and　have　varying　Hf-isotope　crustal　model　ages　of　731-839　Ma.　The　geochemical　and　isotopic　compositions　indicate　that　magma　of　the　Liemai　granite　can　most　likely　be　interpreted　as　products　of　the　break-off　related　to　thermal　perturbation　along　the　break-off　window　associated　with　the　subduction　of　Neo-Tethyan　slab.　These　magmas　were　derived　mainly　from　the　anatexis　of　ancient　crustal　materials　under　contraction　and　thickening　conditions　due　to　subduction　of　the　Indian　continent　beneath　southeastern　Tibet.