Abstract: Network security situation awareness technology is a novel technology to defend attacks and intrusions and provide global network security situation in an active and real-time style.The hierarchical realization model of network security situation awareness is built.The corresponding realization method of each layer is put forward respectively,including network security situation element extraction based on multi-classifier fusion,hierarchical situation assessment based on statistical learning and dynamic situation prediction based on back propagation neural network with genetic algorithm.Experimental results show that the proposed realization methods are feasible and reasonable.