Abstract: Having studied GPS data observed from 1999 to 2004, we find that the Gansu-Qinghai block can be divided into two parts and the movement of east part is different from the west. After Ms8.1 Kunlun earthquake the difference becomes more clear. The position of the boundary belt is determined with the geological and geophysical data.It turns out that the strike of boundary belt is NE; Its northern part lies between Jinchang and Wuwei,its middle part lies in the ea st of Qilianshan mountain and the west to Menyuan,its southern part lies in the east of Delinha and the west to Qinghai lake.At last the mechanism of crustal m ovement is discussed.