The rapid urbanization has led to a tightening of land resources， often resulting in structures with small spacing between adjacent buildings. Under dynamic loads such as earthquakes， this may cause excessive relative displacement between adjacent structures， potentially leading to collision-induced damage. This paper proposes an energy-dissipation enhanced torsional eddy current damper （EDE-TECD） for vibration reduction in adjacent structures. The basic structure and operational mechanism of the EDE-TECD are first explained. Based on a rack-and-pinion speed amplifying device， a damping coefficient estimation formula for the EDE-TECD is derived. A simplified motion equation for two adjacent structures with EDE-TECD applied is established， and using the optimization criterion of maximizing the minimum damping ratio between adjacent structures， a numerical search method is employed to obtain the optimal inertial mass ratio and damping ratio for the two-degree-of-freedom adjacent structure system with EDE-TECD. An analysis of the optimal inertial mass ratio is conducted， leading to a design process for the optimal parameters in the practical application of EDE-TECD. Additionally， the vibration reduction performance of adjacent structures with either EDE-TECD or linear viscous dampers is compared. Finally， the influence of structural stiffness degradation on the vibration reduction performance of EDE-TECD is studied. The results show that the optimal inertial mass ratio obtained through numerical search may be negative. Increasing inertial mass ratio does not always improve the damping ratio of the structure’s lower modes. Under 10 sets of earthquake wave tests， the optimized EDE-TECD significantly reduces the relative displacement of adjacent structures under seismic action， with the peak vibration reduction rate averaging 64.79%， which is 8.42% higher than that of linear viscous dampers. And under the El Alamo earthquake wave， when the structure’s stiffness is reduced by 10% to 40%， the maximum decrease in the peak damping rate of EDE-TECD is only 6.29%， and the structure can still maintain good damping performance.