Abstract: A secure offloading scheme is proposed aiming to maximize secrecy capacity in mobile edge computing（MEC）enabled unmanned aerial vehicle（UAV）systems by jointly optimizing the flight trajectory of UAV, transmit power of UAV, offloading ratios of computation task , artificial noise（AN）power and UAV computing capacity. The problem is hard to solve since it involves multiple optimization parameters and non-convex. The problem is decomposed into four sub-problems with block coordinate descent （BCD）method, then, the successive convex approximation （SCA）technique is used to solve each sub-problem. The simulation experiment results show that the proposed scheme significantly improves the secure capacity of the systems.