The crustal movements, probably motivating earthquakes, are considered as one of the main geodynamic sources. The quantitative measurements of ground surface deformations are vital for studying mechanisms of the buried faults or even estimating earthquake potential. A new space2geodetic technology, synthetic aperture radar interferometry (InSAR), can be applied to detect such large2area deformations, and has demonstrated some prominent advantages. This paper reviews the capacity and limitations of InSAR, and summarises the existing applications including some of our results in studying the earthquake2related crustal motions. Finally it gives the outlook for the future devel2 opment of InSAR.