Abstract: The improved Analytic Hierarchy Process (AHP) in conjunction with improved Entropy method is used to handle the ambiguity and uncertainty of the indexes in the navigational safety assessment of Yangshan Port. The optimal values of weights are decided through balancing, with the game theory, the values which would have been chosen respectively otherwise. A grey clustering evaluation model based on the sinusoidal center-point mixed possibility functions is developed, which partially overcomes the weak points of normal grey clustering models. Moreover, introduction of the normalization of weights into the calculation of the possibility function can guarantee the consistency of clustering coefficients, in turn, the accuracy of the clustering results. The assessment method is used for largescale container ships and results a maximum composite clustering coefficient 0.253, meaning low risk, a correct reflection of actual situation.