This paper investigates the potential to acquire flight information, including the spatial position and attitude, of a flapping-wing micro-aerial vehicle (MAV) utilizing a stereo-vision system. The flapping-wing MAVused in this paper is the Golden Snitch developed by the MEMSLaboratory in the Tamkang University. The Golden Snitch has wing span of 20 cm and weight of 8 g. Due to limited loading capacity, a conventional inertia measurement unit cannot be installed onboard. As a result, an external stereo-vision system is a potential solution to navigate a flapping-wing MAV. At beginning, techniques of image processing and stereo vision are briefly reviewed. Then, formulae to obtain flight information through the measurements of the stereo-vision system are derived. Four types of experiments are designed and accomplished to evaluate the performance of the system. Experiment results are provided to demonstrate the applicability and constraints of our algorithms.