Based on the analysis of the factors influencing the navigation environmental the bridge navigable waters,we construct the indices system for the risk assessment of the bridge navigable waters.Based on the fuzzy theory,we build a comprehensive environmental risk assessment model for the bridge navigable waters using Analytic Hierarchy Process (AHP),and carry out a comprehensive risk assessment on the navigation environment of Shanghai-Nantong railway Yangtze River Bridge The result indicates the degree of risks and index factors in dangerous condition,and may serve as reference for the maritime administrative department to improve the navigation condition and maritime administration for the bridge waters.