Abstract: Nuclear energy has a broader application prospect compared to traditional thermal power. The development of efficient and safe nuclear power half-speed turbine generator is the key to the development of nuclear power technology. As the core equipment of the power system, with the increase of the unit capacity of million-kilowatt-class nuclear power half-speed turbine generator, the problems of loss and heat in the end zone become more and more serious. In order to improve the calculation accuracy of the electromagnetic field and losses in the end of nuclear power half-speed turbine generator, a novel 2D-3D electromagnetic field-circuit coupled calculation method is proposed. The distribution of electromagnetic field and end-component losses in the end region of a 1 407 MV·A nuclear power half-speed turbine generator is studied. The stator end leakage reactance is calculated by using the magnetic field energy storage method and analytical method, which is applied to the external circuit of a nuclear power half-speed turbine generator. The coupled calculation is conducted on two-dimensional transient electromagnetic field, three-dimensional end transient electromagnetic field, and external load circuit. Factors such as rotor rotation, material characteristics, and the actual size of complex end components are considered. The distribution of electromagnetic field, flux density, and eddy current density of end components in the nuclear power half-speed turbine generator is studied. The losses of the end components are determined in the nuclear power half-speed turbine generator. Three-dimensional end region fluid-solid coupled model of nuclear power half-speed turbine generator is established. The losses of the end components obtained by the novel calculation method is used as the heat source, and the inlet velocity and outlet pressure value of the end region obtained by the flow network is used as the boundary conditions. The complex fluid flow and temperature distribution of the end components in the end region are obtained. Compared with the measured values, the feasibility of calculation method in this paper is verified.