Abstract: The theoretical researches on defence strategies for special networks in China are briefly introduced and the complexity and security requirements of railway network are outlined. To cope with ever-increasing security threats, a hierarchical dynamic offense and defence game model is proposed. The construction process of such a model is specially divided into three steps in terms of the three functional levels of defence planning and resource allocation, maximization of attack effects, and minimization of attack loss. On this basis, a three layer model oriented to railway network is built and the mathematical expressions of objective functions and constraint conditions of each layer are given and a resolution method is provided.