Abstract: Deformation monitoring is a critical way to understand the evolution of landslides.To research the performance of real aperture millimeter-wave radar for slope deformation monitoring, a photographic slide was used as a deformation simulation device to conduct simulation tests.Combined with the engineering case analysis, it shows that:(1) Real aperture millimeter wave radar has the ability of deformation monitoring; when the photographic slide returns to the origin, the error of real aperture millimeter wave radar is only-4.68 mm and 6.39 mm, which can accurately reflect the deformation characteristics of the photographic slide;(2) A single set of real aperture millimeter wave radar can monitor the horizontal coverage of the angular reflector in the range of 200 m or less, and can get a better deformation information, which can meet the monitoring needs of medium-sized landslides.(3) The feasibility of the principle of 3D coordinate interpretation is verified as a whole.When the deformation amount reaches 970 mm, the interpreted spatial displacement error is 9 mm and the error ratio is less than 1%,and the interpreted azimuth complies with actual landslide movement direction.Comprehensive simulation tests and engineering cases show that the real aperture millimeter wave radar meets the needs of landslide deformation monitoring with strong stability.