According to the microgrid which contains a variety of distributed generations, a Multi-objective optimal dispatching model for microgrid is proposed. These objectives include the operation cost, sewage treatment cost and the comprehensive benefit cost. The multi-objective is converted into a nonlinear single objective optimization problem through the maximum fuzzy membership. Considering the influence of the distributed generation characteristics on the optimal dispatching of microgrid and according to a certain control strategy, the economic operation of the optimum scheme was obtained by Adaptive Simulated Annealing Genetic Algorithm (ASAGA).