The invention provides a coal-fired power plant atmospheric environment impact assessment method and device. The method comprises the steps that the pollutant emission list data are determined according to the parameter data of a coal-fired power plant; the meteorological data of an HYSPILT model are determined according to the historical meteorological data of the simulated time period; and the coal-fired power plant atmospheric environment impact assessment result is generated according to the pollutant emission list data and the HYSPILT model of which the meteorological data are determined.A local small scale diffusion model can be established through the determined pollutant emission list data by using the HYSPILT air quality mode system so that quick computation can be guaranteed, the observation data can be assimilated and great matching with the local terrain can be realized.