Abstract In order to reduce the structural vibrations of a mechanical system used in aerospace, a new sketch of eddy current damper (ECD), consisting of one cylindrical permanent magnet, two ring-shape copper plates, one axial transmission shaft and electromagnetic shield, is proposed. Three dimensional (3D) electromagnetic transient analysis on damping performance of the proposed damper is conducted by ANSYS to determine the dimensions of the designed damper. And a series of damping tests for the damper subjected to sinusoid excitations with amplitudes of around 0.1 and 1 mm are respectively carried out under frequencies ranging from 1 to 50 Hz. The experimental results validate that the 3D transient analysis method with ANSYS is effective to guide the design of ECDs. Moreover, it is found that the proposed ECD has high damping, which is significantly superior to the one-plate ECD with the same structure and dimensions.