Based on the framework of edge computing, this paper proposes a parallel distributed optimization method to solve the complex optimal economic dispatch problem of microgrid containing massive renewable energy, which effectively improves the solution efficiency. In this method, edge nodes only exchange information with neighboring nodes, which reduces the communication complexity. At the same time, each node solves in a parallel manner, breaking the constraints of “combination explosion”, improving the solution efficiency, and obtaining the global optimal solution after multiple iterations. Further, in the microgrid with massive renewable energy, an optimal dispatch model with minimum operating cost is constructed, and the proposed method is used to solve the large-scale optimization model. The simulation results show that, compared with the standard ADMM, the number of iterations of the proposed method is only half or even less than that of the ADMM under the same accuracy. In addition, when the output power of massive renewable energy fluctuates, the incremental cost of distributed power sources tends to be consistent, indicating that after the interactive regulation of the microgrid and the upper-level power grid, the method in this paper can make the microgrid operate stably and minimize the cost at the same time.