Software-Defined Networking (SDN) has been a hot topic for future network development, which implements the different layers of control plane and data plane respec-tively. Despite providing high openness and programmability, the three-layer two-inter-face architecture of SDN changes the tra-ditional network and increases the network attack nodes, which results in new security issues. In this paper, we firstly introduced the background, architecture and working process of SDN. Secondly, we summarized and analyzed the typical security issues from north to south: application layer, northbound interface, control layer, southbound interface and data layer. Another contribution is to re-view and analyze the existing solutions and latest research progress of each layer, mainly including: authorized authentication module, application isolation, DoS/DDoS defense, multi-controller deployment and flow rule consistency detection. Finally, a conclusion about the future works of SDN security and an idealized global security architecture is pro-posed.