Aiming at the application of zooming image distance measurement to mobile robot, the related key technologies are investigated in detail in this paper. Firstly, camera parameter calibration is conducted. The camera focus, optical center displacement between two foci, principal point and aberration coefficients are calculated accurately. Then, robust feature matching based on SIFT is realized by the geometrical constraint of a zooming image. Finally, the 3D reconstruction model of zooming image is established. The experimental results based on real sample images validate the practicability of the related algorithms.