The definition and the main features of active distribution network (ADN) are introduced, the new technologies and the key design factors of active distribution networks are stated, the necessity and the feasibility to integrally design active distribution networks are clarified, and an integrated design method is proposed. In order to get the optimized scheme of active distribution network, “step-by-step progressing” strategy and “one-step-one-feedback” correction method are used in proposed integrated design method. The main circuit connection modes, the distributed generation systems, the data acquisition devices, the communication system, the protection devices, the automation of distribution network, the operation dispatching system, and the implementing conditions are included in the optimized scheme. The design flow is introduced in detail.