Abstract: In order to analyze UF₆ leakage accident in detail, including the leakage flow changes and the behavior when it leaks into the room, based on the mass and energy balance in the UF₆ container and the mass balance in the room, a source term analysis model of UF₆ indoor release is established. This model is used to analyze the typical UF₆ leakage accident in the safety analysis report of domestic uranium fuel fabrication facilities. Some information are obtained, including phase change, leakage flow and the change of leakage state in the container, the concentration and deposition of hazardous materials in the room after leakage, and the concentration of hazardous materials eventually discharged into the environment, which can be used for the implementation of emergence plans and environmental impact assessments.