Abstract: Directed at the proposed earthquake reduction system， named the tuned tandem mass dampers （TTMD）， the optimized analysis of the multi-degree-of-freedom （MDOF） structure-TTMD system has been investigated in frequency domain by the parti? cle swarm optimization. The seismic simulation of the MDOF structure-TTMD system has been established under earthquakes. Considering different types of seismic records， the control efficiency of TTMD for the structural seismic responses was analyzed in the time domain and compared to that of the tuned mass damper （TMD） with the equal total mass ratio. Further taking into ac? count the structural stiffness of the -10% and -30% degradations， the earthquake reduction behaviors of TTMD were scruti? nized for the seismic responses of the structure with the stiffness degradation. It is found in terms of numerical results that the TT? MD outperforms the TMD in seismic performance and robustness. Likewise， the TTMD has a drastically reduced damping de? mand， thus being an enhanced earthquake reduction system.