To process uncertain data obtained in sensors,a model of Situation and Threat Assessment (STA) based on fuzzy Bayesian network was proposed. The uncertain sensor data were divided into vagueness domain and probability domain. The vague data type of the threat target was handled by fuzzy comprehensive evaluation,and the dynamic threat degree was obtained in fuzzy domain. And then the fuzzy dynamic threat degree was translated into the probabilistic type by the possibility/probability theory. All the uncertain data were figured in probabilistic type and processed by Bayesian network to produce the threat level of the target. An example indicates that the fuzzy Bayesian network can obtain the real threat levels and is feasible for weapon system to automate decision-making on target-selecting and target-striking.