In this letter, an optimal operation model for amultiagent system (MAS) based microgid is proposed. The objective is to save the overall energy cost represented as a sum of locally observable convex functions. An asynchronous and distributed alternating direction method of multipliers (ADMM) algorithm is developed for theMAS-based microgrid to solve the formulated optimization problem and reach a convergence state. The proposed approach is shown to be highly effective through a simulation case study, indicating high potential for applications.