The reliability of brake disc bolts is crucial to the operational safety of high-speed electrical multi-units (EMUs). It is of great significance to investigate the bolt loads to ensure the bolt service life. A theoretical analysis is completed according to the jointed structure and the service condition of the bolts. By establishing a finite element model of the wheel-rail contact, the bolt loads of the wheel-mounted brake disc under high-speed rotation are simulated. A field experiment is implemented to obtain the dynamic loads of wheel-mounted brake disc bolts of a Chinese high-speed train based on a load test technique. The tested bolt loads include the tensile force, radial bending moment and circumferential bending moment. The simulation results are compared with the field test data. It validates the finite element model. The results indicate that the bolt loads are closely related to the operation speed of the high-speed EMU. The theoretical calculation method and the finite element method both prove that the amplitude and the direction of the radial bending moment along the bolt are inconsistent. The extrema of the radial bending moments appear in the left, middle and right cross-sections. The radial bending moment at the left cross-section is larger than that at the right cross-section because of the asymmetry of the wheel structure.