Abstract: Facing the issues about the vulnerable transmission links or the limited transmission coverage caused by the deployment of Internet of things (IoT) devices in remote areas, unmanned aerial vehicle (UAV) and mobile edge computing (MEC) technology in this scenario was introduced to deal with the problems effectively such as the limitation of energy supply, the shortage of computing capacity, as well as improvement of communication coverage and reduction of unnecessary network overhead. In addition, the introduction of blockchain technology ensured the security and reliability in the process of data interaction, and accomplished data sharing. Therefore, a resource allocation decision method based on MEC and blockchain was proposed for UAV-assisted IoT system. To achieve the optimal trade-off between the performance of MEC system and blockchain system, a problem model was formulated by considering the allocation of spectrum resource and computing resource, then a distributed optimization method was adopted based on alternating direction method of multipliers (ADMM) to solve the problem. The simulation results demonstrate that the proposed optimization scheme can reduce the total energy consumption of MEC system and the computation latency of blockchain system effectively. Meanwhile, the proposed scheme has better convergence performance and the stability of the system can be well guaranteed.