An earthquake of magnitude 7.1 suddenly occurred in Yushu county of Qinghai province on April 14

2010. This paper presents the studies of using the data of Advanced Land Observing Satellite-Phased Array type L-band Synthetic Aperture Radar （ALOS-PALSAR） before and after the earthquake to examine and calculate the co-seismic ground deformation. The dif-ferential SAR interferometry （D-InSAR） technique is used. The results show that the earthquake caused the ground deformation over a large area. The extension of the ground deformation followed the south-east to east direction and along the Yushu-Ganzi fault zone. The largest deformation was found about 350 mm at 33.7°N 96.81°E. It is along the line of sight （LOS） of SAR and can be detected with D-InSAR technique. The detected ground deformation was mainly uplifting. The detected ground deforma-tion has an important value for evaluating the extent of ground damage and seismicity in Yushu after earthquake

inferring the nature of the quake faulting

and studying characteristics of seismic deformation.