A method and a system for providing an overlay network interworking with an underlay network are disclosed. The method for providing the overlay network interworking with the underlay network comprises a method for providing an overlay based virtual network between data centers (DC) connected with a wide area network (WAN), the method comprises the steps of: identifying accessibility between a source customer system connected to a first network virtualization device included in a first DC and an object customer system connected to a second virtualization device included in a second DC by a network virtualization management device; transferring forwarding information obtained by interworking with the first network virtualization device to the second virtualization device by the network virtualization management device; and configuring a path so as to perform a tunneling process between the first network virtualization device and the second network virtualization device using information on a WAN section and a control command by the network virtualization management device.