To get the 6D parameters of an object, two cameras are at least involved in the system to shoot at different positions so that the stereopair with a certain parallax can be obtained, and then the space parameters of the object will be worked out through space intersection. By changing the classical photogrammetric collinearity equations, parameters to be solved are taken as equation parameters to obtain extended collinearity equations. When the rigid object have three or more reference marks of known coordinates, the 6-dimensional space parameters of target can be got by use of single frame images. Because of fewer cameras to be needed, the technique can be applied to the occasions that too many cameras are not allowed to be installed , such as flight testing, aircraft components docking.