The unmanned aerial vehicle (UAV)-assisted mobile edge computing (MEC) networks exist security and privacy issues on task offloading, which can not be tackled by conventional security mechanisms. In this article, we consider consortium blockchain combined with UAV-assisted MEC networks to overcome these challenges. An improved Delegated Proof of Stake (DPoS) consensus scheme is designed in which the UAVs act as light nodes to collect the tasks and verify their signatures from the ground users to form the initial block and then offload it to the ground blockchain nodes for final block generation. We ensure the trustworthiness of the ground blockchain nodes through voting by the reputation incentive mechanism. The two-stage the UAV and ground blockchain nodes by jointly optimizing the trajectory and communication resource allocation of the UAV and computing resource allocation of the ground blockchain nodes. Furthermore, we analyze the Stackelberg equilibrium by the backward induction and adopt the approximate convex algorithm (SCA) to approximate the non-convex problem solving. Simulation results demonstrate the effectiveness of the developed scheme for trusted management and superior delay.