In this paper,PS reflection was used to determine the depth and fluc-tuation of Moho discontinuity in the local region of the north side of the Yarlung Zangbo River.
A clear PS reflection was recorded in the radial direction of the Ya-dung-Dang Xiong profile the apparent velocity is 8.35±0.28Km/s.
Travel times of pp and PS phases reflected at the same part of the Moho were used to determine the structures of lower crust,the dip of Moho discontinuity is-0.83°-0.84° and its depth is about 68-69 Km.The range of fluctuation of Moho is 120Km and the extent is about ≥ 1Km.The result indicates that fluctuation of Moho is slightly changed and the crust is fundamentally horizontal.The authors recognized that PS reflection could be very useful for the determination of flactuation of Moho and for the study of the inner cru-stal structure.