Abstract: With the development of aerospace imaging technology, the demand for remote sensing imaging observation system is increasing. In order to simplify the alignment and assembly complexity of the optical system and reduce the volume of the optical system, a designed method for low-cost and miniaturized remote sensing imaging optical system was proposed. On the basis of all spherical lenses and low dispersion materials such as calcium fluoride, an optical imaging system with a focal length of 2 000 mm and suitable for 5.08 cm (2 inch) detectors was designed. The modulation transfer function (MTF) was greater than 0.41 at 50 lp/mm, and the volume was close to the R-C system. The spherical primary and secondary mirrors of the system avoided the use of aspheric compensators during alignment and adjustment, which reducing the cost. The structure of a new type of louver baffle was designed to effectively avoids the problem of excessive volume of the conventional outer baffle structure. After the avoidance angle is greater than 12°, the point source transmittance (PST) value is less than 10^-6, and the optical volume is only ϕ227×421 mm³, much smaller than the conventional outer baffle form. The system offers advantages of low cost, miniaturized structure, light weight, excellent image quality, and good stray light suppression, which can meet the requirements of aerospace imaging system in engineering applications.