Abstract: Based on the heterogeneous network architecture, in this paper by taking into account the mobile edge computing (MEC) architecture of Internet of things in power systems using three-tier computing, the energy consumption model and delay model are established respectively for each tier. Then the related tasks are offloaded from local computation in smart mobile device (SMD) to the MEC servers of small base station (SBS) and macro base station (MBS). To minimize the energy consumption due to the computing offloading, through variable substitution and decomposition, then by taking advantage of theoretical derivation based on the objective function monotonicity, the optimal solution is finally obtained. Simulation results show that, in comparison with other methods, the proposed scheme can achieve the effects of energy saving with less time delay.