Scenery changes on the earth are utilized for space remote sensing cameras to perform imaging during flying around the earth. The larger field of view a space remote sensing camera has, the larger observation area on the earth the system will obtain. However, high-resolution imaging is usually achieved by using an optical system with large aperture, which will lead to more aberration. This will further limit the field of view of the system. At present, the remote sensing cameras equipped in most satellites cannot have both large-field-of-view detection and high-resolution recognition. Aiming at this problem, a compact space remote sensing camera with large-field-of-view search and multi-band high-resolution imaging is designed in this paper.The integrated optical system with functions of large-field-of-view search and high-resolution imaging is shown (Fig.10). A primary mirror with large aperture is shared by the large-field-of-view search module and the high-resolution imaging module, to reduce the weight and overall size volume of the system. Cassegreen structure is adopted in the high-resolution imaging module, involving a visible-light imaging module and a mid-wave infrared imaging module, which are splitted by the secondary mirror. An off-axis four-mirror structure is adopted in the large-field-of-view search module. Two freeform mirrors with the Biconic-Zernike shape are used to correct the aberrations.In this paper, an optical system for a compact space remote sensing camera with both large-field-of-view search and high-resolution imaging is proposed. The overall weight of the optical system is about 140 kg, and the overall volume is 0.8 m×0.8 m×1.1 m. The focal length of the large-field-of-view search module is 945 mm with field of view in the sagittal direction of 10°. The diameter of the entrance pupil is 130 mm and the working waveband is 0.45-0.9 μm. The optical structure is shown (Fig.1). The resolution of 4 096×4 096 for the detector is adopted with pixel size of 15 μm×15 μm. When the orbit height is 500 km, the system can search the ground with line width of 33 km and ground resolution of 8 m. The high-resolution imaging module is composed of a visible light imaging module and a mid-wave infrared (MWIR) imaging module. The focal length of the visible-light imaging module is 4 200 mm. The resolution of 6 252×4 176 for the detector is adopted with pixel size of 3.76 μm×3.76 μm. The MWIR imaging module has a focal length of 4 000 mm, a detector resolution of 384×288 and a pixel size of 25 μm×25 μm. A large-aperture primary mirror is shared by a visible-light module and a MWIR imaging module, with the same diameter of 800 mm. When the orbital height is 500 km, the visible-light and MWIR imaging modules can image the area of 2.813 km×1.879 km and 1.228 km×0.922 km respectively, within the full field of view of 0.4°. The ground resolution for the visible-light imaging module and MWIR imaging module are better than 0.45 m and 3.2 m respectively. The tolerance values are given according to the processing requirements. The tolerance analysis of the system is then carried out, in which the random-statistical method is used in the search module to perform surface-tolerance analysis on freeform surfaces. The analysis results show the MTF values of the visible-light imaging module, MWIR imaging module and search module within full FOV are all greater than 0.2 at Nyquist frequency (133 lp/mm, 20 lp/mm and 33 lp/mm). The optical system can meet the requirements of actual processing and assembly.With the rapid development of space remote sensing technology, space remote sensing cameras need to obtain larger field of view and higher resolution. In this paper, an optical system in remote sensing camera is proposed, involving a high-resolution imaging module and a large-field-of-view search module, which has the functions of both large-field-of-view search and multi-band high-resolution imaging. The system has a compact structure, which is beneficial to realize miniaturization and lightweight of the system. The optical system has certain reference value for the design of multi-mode satellite optical payload.