Abstract: Located immediately in the inner Southern Tibet detachment in the Dingjie region,South Tibet, leucog ranites in the High Hima layancry stalline basement are S-type granites and in truded with two different periods,earlier biotite leucog ranites and later muscovite leucog ranites. The leucog ranites veins occurred widesp readly in the parametam orphic rocks,in which the hypersthene mela-granulited istributed.That suggests the source rocks of leucog ranites of the High Himalaya are parametamorphic rocks. For the ba sement was uplifting,pressure relieved and lacked water,source rocks were melting partly and formed the leucog ranite magma.