Abstract: Radar corner reflector plays an role of post-strike in the field of radar countermeasures, which can interfere with the detection of enemy radar and protect important facilities of one’s own side. The traditional corner reflector is made of metal plate as the reflecting surface. Although it has the function of strong reflection, its weight is larger. Once it is processed and formed, its shape and size are fixed and the scattering characteristics are single. Therefore, it cannot meet the increasingly complex application requirements. In order to solve the above problems, a design method of novel ultra-lightweight radar corner reflector structure with adjustable radar cross section (RCS) is proposed by considering the weight, scattering characteristics and adjustability of the corner reflector. The method uses carbon fiber rods with high structural strength as the supporting frame and large flexible wire mesh as the reflecting surface of the corner reflector. The structure is designed with the function of unwrapping folding, so that it can be continuously changed between different structural states, so as to achieve the purpose of RCS regulation. In order to verify the feasibility and effectiveness of the design method, a 1m aperture 12-unit deployable corner reflector array prototype was developed. The novel radar corner reflector has a weight of only 1.325 kg, and can regulate RCS smoothly through the deployable state switch, and is easy to be loaded and transported, which is suitable for a variety of carrier platforms. After experimental testing, it can achieve substantial regulation of RCS. More than 10 dBsm regulation amplitude can be reached for most frequency bands in the 2−20 GHz band, and it can exceed 30 dBsm for a few frequency bands, which proves that the regulation effect is good. This design method can provide reference for the design of ultra-lightweight corner reflectors with adjustable scattering characteristics.