Considered battlefield situation assessment is beneficial to the warfare command and decision-making. Complex warfare situation leads to using an innovative situation assessment approach which be built upon the domain knowledge system and credible reasoning methods. The knowledge system and the uncertain reasoning methods within warfare domain were reviewed and discussed in this paper. Several relative confusable conceptions ware distinguished and the knowledge classifications was summarized firstly, then discussion on the structure of knowledge bases was bright up, which given rise to the uncertain knowledge representation issues. So the significant uncertain theories and reasoning means to handle domain knowledge uncertainties were described and compared in the end. The contents of this research will be guidable to academically study and extend the patterns of the battlefield situation assessment.