Abstract:In this paper, using GPS observations of crustal movement observation network of China(CMONOC) from 1999 to 2015, we obtain the horizontal velocity field of the western Yunnan rhombic block, which is located in southeast of the Qinghai-Tibet plateau. It turns out that direction of the present-day crustal movement of this area, relative to the Eurasia plate, generally shows a clockwise rotation from east to southeast and from southeast to southwest. The magnitude of velocity in this research area shows that the value of velocity in the middle of rhombic block is greater than that on the sides, and the value shows a reducing tendency from north to south. The maximum shear strain rate of this area, calculated by triangle method, shows that higher valuesare concentrated in the east and west border of rhombic block. The direction of principal strain shows the state of east-west compression and north-south stretch. The fault zone on the east side of western Yunnan rhombic block presents sinistral movement and the fault zone on the west side presents right-lateral movement, which is identical to the results from geological survey.