Abstract: In this paper, based on the previous study of practical use of seimic situation windows and seismic situation belts, the problem of establishing a seismic situation network consisting of windows and belts is further posed and discussed according to the observed fact that many windows and belts make responses to one earthquake. For the convenience of usage, the seismic situation network is divided into two classes, the first class and the second one. The former can be used in tendency prediction for long-term seismic activity in a large area, the latter used in shortterm prediction in a small area. In this paper, after briefly discussing the physical significance of seismic situation network, it is pointed out that this simple and easily used method can be used to observe and extract seismic precurssory information from a large area before a great earthquake, thus it can provide a reliable basis for the analysis and judgement of seismic situation tendency in time and space. No doult, this method is of certain practical significance.