Aiming at the technical difficulties of the cantilever scanning corner mirrors assembly of spaceborne Michelson interferometer， such as multi-dimension， high precision， difficult detection and etc.， a method of "vector analysis + precision micro-adjustment" was proposed， which included establishing the installation and detection benchmark， simplifying the angle mirrors to a spatial point vector， adopting the adjustment sequence of "first method to back plane" and using special precision micro-motion device， etc. And finally the high-precision adjustment of the spatial multi-degree-of-freedom angle mirrors assembly was realized. After the adjustment， the symmetry of the vertex position of the angle mirrors reaches 0.008 mm， which is superior to the design accuracy of 0.01 mm. The adjustment accuracy is improved effectively and the adjustment cycle is shortened.