The invention relates to a radar differential interference deformation measurement method comprising the following steps of S1, placing a radar at a high place via a radar mounting platform; S2, measuring and recording a radar antenna position via the measurement device; S3, moving the radar mounting platform along a set track, synchronously transmitting a radar wave to an observation area and recording an echo by using a radar system, and synchronously measuring and recording the radar antenna position by using the measurement device; S4, acquiring radar image data via imaging treatment by using the radar antenna position measurement data and the radar echo; S5, observing a same target for many times, and acquiring multiple times of radar image data of the target area; and S6, acquiring the deformation of the target area via differential interference treatment and atmosphere delay correction. According to the method provided by the invention, the radar is placed at the high place, sothat the radar measurement range is enlarged.