Reasonable coordination of various types of grid-connected intermittent energy, energy storage devices, flexible load and other controllable devices is an effective way to achieve the optimal dispatch of active distribution network. Based on the setting of various energy dispatching order and the control scheme of segment switches, the three-tier framework of multi-source coordinated optimal dispatching model was constructed from the three aspects of environment, operation and economy, meanwhile, using an improved seeker optimization algorithm mixed with the core idea of frog leaping algorithm and genetic algorithm to solve it. Finally, simulation results showed that the multi - source coordinated optimal dispatch can effectively improve the accommodation rate of renewable energy, smooth loads fluctuation, reduce network power loss and improve user experience, verify the rationality and superiority of the optimization scheme.