: Network security situation awareness (NSSA) is a hotspot in the network security research field, and it’s the perception, comprehension, and forecast of network security situation, based on the security situation values, decision- makers can be aware of the actual security situation of their networks and then make rational decision to make their networks safer. In this paper, we build a multi-level quantization model for NSSA firstly; this model is comprised of three levels, namely, special oriented level, essential oriented level and holistic level. We can not only perform a certain kind of situation awareness, but also an overall one using this model. Different from the previous methods which compute network security situation of whole network just by summing up the values of each asset’s network security situation values, we propose a novel algorithm based on exponential and logarithmic analysis, this novel method is more appropriate to obtain rational results. Our model and a...