Abstract: In order to further improve the real-time imaging processing ability of synthetic aperture radar (SAR) in the face of massive echo data, the optical and mechanical system of SAR real-time imaging optical processor is designed and analyzed based on 4f optical structure. Firstly, a Fourier transform lens with an entrance pupil diameter of 21 mm, a field angle of 7°, and a focal length of 172 mm is designed for the filtering algorithm, and a compact design is adopted for the 4f optical system. Then, the flexible mirror base in 4f optical mechanical structure is optimized by using the integrated optimization method, and the overall structure is modularized designed and analyzed. The results show that the imaging quality of 4f optical system tends to the diffraction limit, and the MTF of Fourier transform lens is better than 0.57 at 55 lp/mm. The RMS value of lens surface shape of 4f optical mechanical system under normal temperature 1g gravity condition is less than λ/50. The fundamental frequency of the overall structure is greater than 100 Hz. The overall size of 4f optical processor is 405 mm×145 mm×92 mm, the mass is about 2.94 kg, and its volume and mass are only 30% and 48% of those of oblique plane optical processors with the same SAR data processing level. Through data simulation, it shows that the system design meets the needs of real-time imaging on satellite or airborne.