Abstract: Accurate and rapid simulation of the hysteresis characteristics of silicon steel sheets with small biased hysteresis loops under non-sinusoidal excitation is an important part of the optimal design of transformers and motors and other power devices. The existing inverse Play model requires a large number of measured values of concentric hysteresis loops or first-order reversal curves under different magnetic densities when simulating the hysteresis characteristics of silicon steel sheets under non-sinusoidal excitation, and the simulation accuracy is low at low magnetic densities. To solve this problem, we propose an improved inverse Play model. First, the non-uniform interval first-order reversal curves data generated by the numerical method are adopted to adjust the Play hysteresis operator threshold and the hysteresis operator sequence, and the shape function parameters of the inverse Play model are extracted. Then, the triangular excitation is used to replace the non-sinusoidal input excitation. Based on the new input excitation and shape function, an improved inverse Play model is established which can be adopted to accurately simulate the hysteresis characteristics of magnetic materials under non-sinusoidal excitation. The improved inverse Play model only needs the experimental data of high, medium, and low hysteresis loops of silicon steel sheets, and the hysteresis characteristics simulation results and loss calculation results of silicon steel sheets under different harmonics are compared with the experimental measurement data. It is found that the global errors are controlled within 10%, verifying the accuracy and practicability of the improved inverse Play model proposed in this article.