In order to solve the problems of narrow detection band and low resolution of space-to-ground remote sensing optical system, an aspheric off-axis triple inverse optical system is designed. The off-axis field of view of the computed coaxial tri-reflective structure is processed, the aberration is optimized, and the imaging quality of the off-axis tri-reflective system is analyzed and evaluated. The resolution of the designed optical system is improved in the visible and short- and mid-wave infrared bands, reaching 2 m, 3.3 m and 10 m ground resolution, respectively. The system has three reflectors with even aspheric surface, 600 mm focal length, 1/4.3 relative aperture, 8°×4° field of view and 0.4% maximum aberration. The MTF value at Nyquist frequency is higher than 0.2 for each band, and the RMS radius meet the imaging requirement of less than the minimus image element size of the detector. The high resolution and wide band design objectives have been achieved, thus enhancing the system's all-weather information acquisition capability.