Multi-access edge computing (MEC) systems where the base station (BS) is equipped with multiple antennas are basic application systems in the future. Moreover, unmanned aerial vehicles (UAVs) can be used as relays for responding to emergency service situations in the systems above. Thus, in this work, we investigate a UAV-relaying-assisted MEC system with multi-antenna BS. The optimization for offloading and scheduling strategies should be considered for the energy consumption minimization. First, a circular deployment scheme is adopted to overcome the difficulty of UAVs’ location optimizations. Then, the original problem is established, which aims to minimize the weighted sum of transmission and hovering energy consumptions by jointly optimizing offloading and scheduling strategies. Moreover, the non-convex original problem is transformed into four sub-problems and their optimal solutions are obtained by proposed algorithms. Finally, an iterative algorithm is proposed to obtain a sub-optimal solution of the original problem. Simulation results show that the proposed algorithm outperforms the three benchmark algorithms in terms of the weighted sum and approaches the performance of the relaxed lower bound algorithm. Furthermore, simulation results demonstrate that appropriate number of UAVs and BS's antennas can achieve better energy-saving performance.