The invention provides a double-field-of-view stereoimaging optical system based on an integrated shared primary mirror, which consists of a two three-reflector abaxial optical systems and comprises a welding primary mirror, two secondary mirrors, three third mirrors, two plane deflection mirrors and two receiving surfaces. Through using two beams of symmetrical deviated field-of-view incident light rays, stereopairs are formed through the optical systems, and the invention can be used for realizing the spatial stereometric mapping with large base-height ratio and high precision. The system of the invention welds the two main mirrors of the two optical systems at a certain angle for realizing the integration of the optical systems, and the stability of the included angle between the front field of view and the back field of view is ensured, so the stability of the base-height (B/H) ratio is ensured, in addition, the welding angle can be changed, and the required base-height (B/H) ratio can be flexibly realized. The system of the invention has the advantages of light weight, small size and high thermal stability, so the high stability of inner orientation elements can be obtained, and the high-precision correction on the images is realized.