In order to address the impact of nuclear accident on the atmospheric environment, an analysis method for the atmospheric diffusion characteristics of radionuclides at different scales was established, which was based on the regional scale weather prediction model weather research forecasting model (WRF). Taking multiple nuclear power plants in the eastern region as the research object, the atmospheric diffusion distribution characteristics of radionuclides released from nuclear accident in the eastern region and in the nuclear power plant surrounding region were studied. The WRF model was used, which was driven by final reanalysis data (FNL) reanalysis meteorological data, combined with the Gaussian atmospheric diffusion model. The results show that the maximum atmospheric diffusion factor at the regional scale mainly distributes in the western region of the calculation area, and it shows a decreasing trend with increasing distance. The difference of the maximum atmospheric diffusion factor at distances of 500 m and 5 000 m is about one order of magnitude. The maximum atmospheric diffusion factor of nuclear power plant surrounding region scale is one order of magnitude lower than that of the regional scale. The difference of the maximum atmospheric diffusion factor at distances of 500 m and 5 000 m is about one order of magnitude for other nuclear power plants, except Qinshan Nuclear Power Plant. There are significant differences of the direction of the maximum atmospheric diffusion factor among different nuclear power plants due to the influence of meteorological conditions of the plant site. The atmospheric diffusion capacity in eastern coastal region is stronger than that in inland region, which is conducive to the atmospheric transport of radioactive radionuclides.