A significant problem of turbogenerators on complex end structures is overheating of local parts caused by end losses and complex fluid flow in the end region. Therefore, it is important to investigate the 3-D flow and heat transfer process in the end. Using a 200-MW air-cooled turbogenerator as an example, the influences of end cores and the actual shapes and material of the end coils, press finger, press plate, and copper shield are considered for the end field calculation; then, the physical and mathematical models of the coil end with involute portions are created. The 3-D electromagnetic field was calculated and the losses of different parts in the end and its distribution were obtained. Based on this, the losses from magnetic field calculations will be applied to the end as heat sources in the temperature field. For symmetry of the ventilated structure, the fluid and thermal physical models of the generator within the half-axial section were determined. A set of equations of fluid flow and heat transfer were derived from the fluid-solid conjugated heat transfer and the fluid and temperature distributions were obtained after solving the equations. All of the aforementioned will provide a theoretical basis for the generator safe operation.