There are some uncertainties in practical risk evaluation of navigation environment, which makes it difficult to implement the related work. To make full use of uncertainty information and over⁃ come their negative effect, the cloud model theory and Monte Carlo method were focused on and intro⁃ duced to navigation environment risk evaluation. A navigation environment risk evaluation model based on normal cloud model and Monte Carlo method was constructed and its approach steps were given. In this comprehensive model, the normal cloud model was used as a conversion tool between qualitative de⁃ scription and quantitative expression to fulfill the risk evaluation of model factors; three key parameters of this model were calculated by executing a Monte Carlo process. The feasibility and effectiveness of this comprehensive model were verified by applying it to the comprehensive risk evaluation of navigation environment of Hangzhou Bay Sea-Crossing Bridge Waters. The result shows that the proposed model could be used as an effective method to evaluate navigation environment risk in case of uncertainty.