Abstract: The method for estimating ship motion conflict is developed for ship collision risks perception in crowded harbor waters or dynamic navigation scenarios. AIS Data are mined to find information about involved ships, such as the relationship between 3 variables(the captain, the speed and relative azimuth) and S_DAmin. The dynamic domain model is built based on the information. The uncertainty of ship navigation dynamics and the ship position predictions is taken into account by incorporating random samples in the ship motion model according to the probability density of the uncertainty components, which embodies the Monte Carlo simulation. This allows the conflict risk problem to be solved with deterministic algorithm. Tests show that the method can give accurate risk estimates in a timely manner.