Abstract: The Park-Ang double parameter seismic damage model has been widely used due to the consideration of first exceedance failure and cumulative damage failure in terms of defining the structural damage under earthquake. However, it does not consider the differences between structural failures with different displacement amplitudes. Based on past experimental research, the damage properties of the reinforced concrete columns under different displacement amplitudes were mainly analyzed, and the relationship between the structure damage and the structural energy dissipation was studied. Past experiments indicated the specimens scarcely failed during the elastic stage, but failed when more energy obsorbed during the developing and fail stage. In this study, effective energy dissipation is proposed instead of using hysteric energy dissipation when describing the cause of structural damage during the inelastic stage. It is suggested that the hysteric energy dissipation during the non-elastic stage is termed as the effective energy dissipation that causes structure failure. Based on the assumption of effective energe dissipation, the effective energy dissipation factor is introduced and a modified Park-Ang double-parameter seismic damage model is proposed. The proposed model is verified by the test data of 21groups of reinforced concrete columns.With the same dissipated energy, the effective energy dissipation factor is proved to show the differences between the structural failures led by different displacement amplitudes. The Definition of the effective energy dissipation factor is thusly explicit, the double parameter seismic damage model is improved with higher computational accuracy and less discreteness, it also tell the failure differences between the reinforced concrete columns under different displacement amplitudes and evaluate the damage level of the RC structure well.