In order to better realize the energy recovery and storage of hybrid EVs (HEVs), a switched reluctance starter/generator (SRS/G) with both starting and power generation functions is investigated in this paper. First, the iron loss of SRS/G is mainly studied to reduce the motor loss and improve the power generation efficiency. Then, the energy storage of hybrid EVs can be effectively improved. Secondly, a magnetic flux density (MFD) wave-forms solution method is proposed to solve the difficulty in calculating the iron loss of the SRS/G. Compared with the commonly used finite element method, the proposed solution method has the advantages of simple, fast and small computational amount. Meanwhile, considering the different operating conditions of SRS/G, the iron loss models for both the time-domain and frequency-domain are established. In addition, the calculation formula of the variable coefficient Bertotti three-term loss separation is improved. As the hysteresis loss coefficient, the Steinmetz coefficient and the stray loss coefficient are respectively fitted by the Fourier fitting method. This method is also applied to solve the iron loss of SRS/G. Finally, through an experimental verification, it is indicated that the development of proposed method has high accuracy.