The invention relates to an airborne ultra-wide-angle spherical reflective optical system, which sequentially includes: window glass, a first spherical reflector, a second spherical reflector, a third spherical reflector, and a fourth spherical reflector along the direction of light beam propagation. mirror, folding mirror and focal plane CMOS detector; wherein, the coordinate system where the window glass is located is the global coordinate system, the direction of the Z axis is vertically upward, the direction of the Y axis is in the paper, and the direction is to the left and perpendicular to the Z axis, and the X axis The right-hand rule is satisfied with the Y-axis and Z-axis. The airborne ultra-wide-angle spherical reflective optical system of the present invention is applied to the airborne optical imaging system, the field of view angle reaches 90°, and the spatial resolution of the earth observation can reach 0.2m, which greatly improves the imaging field of view and effectively expands the The ground coverage width and ground observation accuracy have greatly improved the efficiency of earth observation.