Under the global climate change, the massive, unpredictable and disaster-chain effects of marine disasters are becoming more and more prominent, and the losses have increased year by year. So it is important to carry out the risk assessment of marine disasters. Aiming at the uncertainties in marine disaster assessment, this paper firstly analyzed the uncertainties of marine disaster risk based on risk theory and constructed the disaster assessment index system. Then, a Bayesian network for uncertain disaster assessment was proposed based on the Bayesian Network model, and a weighted Bayesian network assessment model was constructed based on subjective and objective weights. Finally, the assessment of marine disaster risk in coastal areas of China was carried out. Experiments show that the evaluation model effectively achieves the risk assessment of marine disasters and has practical operability.