Holographic subsurface imaging radar uses the penetration of electromagnetic waves into non-metallic media to detect and image the interior of the media, which can intuitively reflect the structure and abnormal distribution of objects in the media in the form of images. By adopting the design methods of integrated radar RF front-end, fast high-density spatial sampling and autofocus imaging processing, a holographic subsurface imaging radar with high plane resolution is realized. The system weighs only 2.5 kg and achieves a plane resolution of 2.5mm, which has high detection efficiency and high portability. The application tests of imaging resolution, penetration of different materials, penetration of biological tissues and non-destructive detection of materials were carried out, which verified the feasibility and effectiveness of the design scheme.