To achieve the optimal operation of an active distribution network so as to build an efficient integration and management platform for distributed generation, a real-time economic dispatching method, which takes the power prediction error into account, is used to establish the optimal operation plan of the system. First, by taking the minimum real-time economic operation cost of the current period as the objective function, and considering power balance, equipment operation, energy storage charging and discharging constraints, etc., a real-time economic dispatching model of the hourly scale is established. Then, based on the real-time economic dispatching plan, a revised model of considering the optimal economy of the revised plan under a 15-minute time scale is formulated for the power prediction bias of renewable distributed generation. The simulation example shows that the economic index of an active distribution network in grid-connected mode is better than that of the off-grid mode, unbalanced power adjustment is economically superior to the conventional methods, and the model established in this paper is suitable for active distribution network operation planning. This work is supported by National Natural Science Foundation of China (No. 51621065).