This article proposes an improved dynamic J-A model for calculating iron core losses under non sinusoidal high-frequency excitation based on the study of characteristic parameters of PWM waveform excitation. Under PWM wave excitation, the influence of magnetic field components corresponding to residual losses on magnetic field strength is ignored. Combining the dynamic J-A model and considering the rate of change of magnetic induction intensity as the slope of the magnetic induction intensity waveform under PWM wave excitation, the calculation of magnetic field components corresponding to eddy current losses is improved, and an improved J-A model is obtained. The PSO algorithm is used to identify the model parameters. Calculate the core loss of the simulated hysteresis loop under different magnetic flux amplitudes and PWM excitations with different duty cycles using this model. Finally, the magnetic properties of soft magnetic materials under high-frequency non sinusoidal excitation were measured on the iron-based amorphous magnetic ring of 1K107 strip using a high-frequency non sinusoidal excitation platform. The iron core loss was experimentally measured under PWM wave excitation with different magnetic density amplitudes and duty cycles, and the differences between the simulated and experimental results were analyzed to verify the accuracy of the improved model.