Abstract: The transport and transfer of radionuclides in the ecological environment (referred to migration) have long been of a particular concern in the field of radiological environmental protection. This paper systematically reviews the current relevant research statuses on mechanisms, models and parameters of radionuclide migration in the ecological environment, and the methods for assessing doses of humans and non-human species, as well as the non-equilibrium migration models and parameters of radionuclide migration in case of accident at a nuclear facility. From multi-dimensional perspectives, such as computational models, evaluation methods, and parameters, etc., this paper explores the transport and transfer behaviors of radionuclides in the ecological environment. In terms of radionuclide migration, this paper systematically reviews the transport processes and migration models of radionuclides from source term release to atmospheric, terrestrial, surface water (rivers, lakes, etc.), groundwater, and marine environments. It elaborates on the basic theories of radionuclide transport and transfer in the ecological environment, compares the characteristics of different transport modes, and summarizes the transport and transfer behaviors of radionuclides in the ecological environment. In terms of environmental radiation exposure assessment, this paper summarizes both individual-related and source-related evaluation methods, describing the basic methods of environmental radiation exposure assessment. It presents a schematic diagram of the main steps and dose estimation models for assessing the impact of radionuclides released into the environment, and sorts out the methods, evaluation models, and dose assessment software for exposure assessment from the perspectives of both the human and non-human species, domestically and internationally. Moreover, for environmental radiation exposure assessment in case of accidents, this paper takes tritium and ¹⁴C as examples to provide an overview of short-term migration, accident exposure assessment, and real-time consequence evaluation and decision support for nuclear accidents. It proposes suggestions for further research in the aspects of radionuclide marine transport, dose assessment models for non-human species, short-term accidental release, and the application of artificial intelligence, to provide scientific basis and technical support for nuclear and radiation emergency response, environmental monitoring, and risk assessment.