Abstract: To address the challenges of high complexity and low accuracy in three-dimensional fluid field calculations for high-speed permanent magnet motors, this study proposes an electromagnetic-flow-heat coupled modeling method that considers the effects of laminar flow, turbulent flow, and their transitional regions. A three-dimensional electromagnetic-flow-heat coupled computational model for high-speed permanent magnet generators is established. The convective heat transfer coefficient from fluid field calculations serves as boundary conditions for temperature field computations, while transient electromagnetic field-induced loss values at different locations act as heat sources. Using the finite volume method for coupled fluid-temperature field calculations, this approach reveals complex velocity and temperature distribution patterns within the generator. Consequently, it determines the stress distribution on the rotor under combined thermal stress and centrifugal force effects.