This paper presents a situation assessment system structure of the warships-airplanes joint operation and a new situation assessment algorithm based on parameter learning in.Bayesian network.Previously,situation assessments are usually operated by using a normal kind of Bayesian network with immutable probability distribution,which may cause the evaluation is too subjective.Therefore,a Bayesian assessment network with parameter learning is considered for a more objective result of the situation assessment.Then a new assessment algorithm of the parameter learning is discussed,which will improve the performance of the assessment.Finally,a model of the battlefield situation assessment of the warships-airplanes joint operation is presented.Its situation assessment simulation results verify the effectiveness of the proposed algorithm.