Aiming at the problems of numerous, complex, heterogeneous and lack of unified data model of knowledge level of spatial situation, which is not conducive to the commander to quickly and accurately obtain the required situation information, an ontology based spatial situation knowledge-based modeling method is proposed. The space situation elements are classified, and a 5 steps method of space situation ontology construction is proposed. With the help of Protégé software, the space situation information ontology database is constructed, and is instantiated with a certain type of early warning satellite as the background. The results show that the method can provide the basic preparation for further using the spatial situation information knowledge for battlefield aided decision-making.