This paper demonstrates the development of a moving point source (MPS) model for simulating the atmospheric dispersion of pollutants emitted from ships under movement. The new model is integrated into the chemistry transport model EPISODE-CityChem v1.3. In the new model, ship parameters, especially speed and direction, are included to simulate the instantaneous ship positions and then the emission dispersion at different simulation time. The new model was then applied to the shipping emission dispersion modelling. The simulated instantaneous and hourly-averaged emission concentrations were compared to those obtained by the commonly-used line source and fixed point source models. More realistic results were observed by using the new model. Furthermore, the simulated results were compared to the measured values at different locations, and reasonable emission concentrations can be predicted by the moving point source model.