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 design method for low-cost miniaturized remote sensing optical system is proposed. On the basis of all spherical lenses and low dispersion materials such as calcium fluoride, an optical imaging system design with a focal length of 2000 mm and suitable for 2-inch detectors has been completed. The modulation transfer function is greater than 0.41 at 50 lp/mm. The volume is close to the R-C system. The spherical primary and secondary mirrors of the system avoid the use of aspheric compensators during alignment and adjustment, reducing the cost of alignment and adjustment. The structure of a new type of louver baffle is designed to effectively avoids the problem of excessive volume of the conventional outer baffle structure. After the avoidance angle is greater than 12°, the PST value is less than 10-6, and the optical volume is only ϕ227×421 mm, much smaller than the traditional form of outer baffle. The system offers advantages of low cost, miniaturized structure, light weight, excellent image quality, and good stray light suppression. In engineering applications, it can meet the needs of aerospace imaging systems.