Abstract: Ground-based interferometric radar can realize small regional-scale continuous deformation monitoring with high-accuracy. To investigate the deformation detection capability and accuracy, a set of accuracy verification platform and system are established in this paper. The corner reflectors are arranged at different positions on the roof and the stepping platforms are used to control the corner reflectors and simulate deformation in different values. The deformation corner reflectors, stable points and the surface of the roof constitute a small two-dimensional deformation field. We use the IBIS-L system to finish the deformation detection and analysis. The experimental results show that when the millimeter level deformation occurs in the corner reflectors, the average accuracy of deformation detection of the ground-based interferometric radar IBIS-L system is 0.27 mm, while the sub millimeter level deformation occurs the corner reflectors, its average accuracy is 0.11 mm. This system can realize the sub millimeter level deformation detection in small regional-scale. For the small and slow change, this system has better deformation detection ability and reliability.