This paper proposes a maritime Accident Dynamic Simulator (MADS) method from one ship’s perspective of ship collision accident. The MADS model is built based on discrete dynamic event trees (D-DET) to generate the time-dependent ship collision accident scenarios. According to the characteristics of maritime activities, such as high freedom of participation, the big influence of the environment, and the high uncertainty, the MADS method is modified, and the analyzed ship collision scenario is reasonably simplified. Both crews’ decision-making process and ship manoeuvre are fully discretized to generate new branches of the D-DET. The interactions between encountered ships are modelled with an information transfer model to form the uncertainties between two ships. The MADS consists of physical simulation engine, crew response and interaction model, reliability model of the system hardware, functional model of human-system interfaces and event sequence controlling model. The MADS starts with a pre-set initiating event under a specific situation. Event branches are discretely generated based on probable alternative state changes of operator response or system evolution. The output probability of an end state can be calculated in the same way with the conventional event tree after the whole scenario completed. At the end of the paper, an accident case study is used to verify the efficiency of the ADS.