Abstract: The accuracy of space-borne InSAR interferometric baseline vector azimuth angle measurement is very important for improving system mapping accuracy. To meet the measurement accuracy requirement of a space-borne InSAR interferometric baseline vector azimuth angle, an optical metrology camera based on image processing is presented, an integrity experiment system is constructed, and the system measurement accuracy is analyzed theoretically. An experiment for optical target assembly with fixed displacement is used to validate the theoretical analysis of the system. The experiment result agrees with the result in theory, the system with arc-seconds accuracy is realized. It proved this approach is feasible for the space-borne InSAR interferometric baseline vector azimuth angle measurement.