In this paper, the authors propose a design of ground-based SAR for digital elevation modulation acquisition and deformation measurement for landslide, and analyse the performance by simulation. A linear guide carries two interference antennas thus the system can both acquire elevation by interferometry and measure deformation by differential interferometry. Considering a general landslide monitoring scene, the geometric model of the antenna movement is established. Then, the spatial resolution and measuring accuracy are introduced through the signal models. A set of specific parameters are designed by comprehensively considering performance and cost. Imaging and interferometry simulations are carried out, whose results demonstrate the deformation measurement accuracy reaches millimetre level and the parameters in designing are reliable.