Abstract Deformation measurement precision of ground-based synthetic aperture radar (GB-SAR) is significantly limited by atmospheric disturbances. To separate the atmospheric and time domain low-pass deformations in high-time-sampling-rate image sequences, an improved permanent scatterer (PS) GB-SAR interferometry method is proposed to monitor microdeformation. The interferometric analysis is based on PSs and image subset series with short temporal baselines. A polynomial atmospheric correction method is adopted to remove the main atmospheric phase of the interferograms and adjust the interferometric phase model accordingly. The linear deformation rates are estimated by a quasi-stable adjustment method guaranteeing the internal coincidence accuracy of the estimation. Spatiotemporal filtering is implemented on the residual phase to obtain the remaining nonlinear deformation to complete the deformation sequence. An experiment was conducted on the Geheyan Dam, China, verifying the GB-SAR results with plummet data. The RMSEs calculated between the deformation series by the two methods were better than 0.30 mm.