The velocity of crustal horizontal movement in the northeast margin of the Qinghai-Tibet block is studied based on GPS data in 1999 and 2001.The area is divided into 9 blocks.The strain and rotation parameters of each block are estimated using the model with rotation in the entire block and linear strain.Then the strain parameters of 104 GPS sites in the area are calculated,and the basic characteristics of the strain field are analyzed.The results indicate that: ① The Alashan block is stable,the rotation re...