Abstract: The terms of surveying results from GPS networks in South Tibet in the past decade provide accurate data for us to study the tectonic deformation of it.We divide the area into 4 blocks of Western Himalaya, Central Himalaya, Kailash and Lhasa bock, establish their elastic motion models.Making Northern Tibet block as referenced frame, we get the horizontal deformation field and strain field of that area.Our result indicates that South Tibet shows very strong S-N shortening and striking E-W extension;The S-N shortening between the south and north border of Southern Tibet is 16.9±2.5mm/a and about 42.4% of convergence between India and Eurasian plates is absorbed.The E-W extensive between Yarlung Zangbu suture and Bangong Co-Jiali fault.is about 16.3±2.4mm/a.Strong push force from the India plate is the main driving force of current tectonic deformation in South Tibet, and the gravity is another important factor.