A regional refined atmospheric environmental emergency response system, targeting at the sudden diffusion of atmospheric pollutants, such as chemical accidents, was developed by the National Meteorological Center. The modelling system, based on the atmosphere dispersion model HYSPLIT_4 and the numerical model WRF, can produce such forecast products as trajectory, concentration, and deposition forecasts with the refined GIS information. The modelling system is available for running on demand and maintained in a state of readiness so that the requests for products can be satisfied quickly. An example of atmospheric environmental emergency response is given, and the results show that the modelling system is able to provide instructive products in case of emergency, such as an accident of toxicgas teakage.