MR dampers are new kind of the most promising devices for structural vibration control. In this paper, an overview of the structure and working principle of shear-valve mode magnetorheological (MR) damper is given. An experimental study was carried out to test the performance characteristics of a shear-valve mode MR damper, its dynamic testing was performed on a Material Testing System (MTS) under sinusoidal and triangle excitation. Based on experimental data, the dynamic characteristics, energy dissipation and dynamic response time were analyzed. The present work lays down a foundation for MR damper application in the semi-active vibration control system.