In the probe-and-drogue refueling system, pilots need to operate carefully to dock probe with drogue, autonomous aerial refueling technology can assistant pilots to accomplish this operation. In this paper, we proposed a novel framework to measure pose of drogue via monocular vision, pose information of drogue can further lead control system accomplish aerial refueling automatically. This framework is consisted of three parts: detecting landmarks of drogue, locating contour of drogue in image, figuring out pose of drogue. Experiment results indicate that this pose measurement system is both accurate and efficient.