The energy ratio method is the commonly used technique for calculating the hysteretic damping ratio of structures， in which the ratio of hysteretic energy to the total elastic strain energy is obtained based on the hysteresis model. However， the method is based on the steady-state response of the structure under harmonic excitation， so it is not extensively applicable to calculate the damping ratio of the structure under a real earthquake. This paper proposes a new method for iteratively calculating the hysteretic damping ratio of the structure. Based on the structural hysteresis damping ratio calculation method proposed by Carlos， and considering the frequency of earthquake wave， the improved formula for hysteresis damping ratio calculation is proposed. The influences of different ductility coefficients and period ratios of seismic to structure on the hysteretic damping ratio are obtained. The results show that the hysteretic damping ratio of different ductility coefficients increases firstly and then decreases with the increase of the period ratio. This study can provide a method for the calculation of the damping ratio of the damaged shock-absorbing structure.