Abstract: To deal with uncertain information of situation assessment in naval battlefield, based on cloud theory and Bayesian network,situation assessment for cooperative searching submarine in anti-submarine warfare (ASW) patrol aircraft is studied. Situation assessment model is established,and the directed acyclic graph of the Bayesian network structure is constructed, the assessment index is determined. Then the cloud model is used for discretization, moreover, the situation assessment process is designed.Therefore, the target type and the opponent′s fighting intention are deduced, and the battlefield situation is formed. Finally, The simulation results show that the proposed method is reasonable and effective.