Abstract: A single coil magnetorheological damper (MRD) was designed, and the mathematical model of damping force was also deduced. In order to obtain an optimal performance of the MRD under a fixed external dimension, the approximate response function of magnetic field density and design variables was obtained based on design of experiments (DOE) and response surface methods (RSM). The objective function was established to obtain the optimal geometric parameters of MRD. The electromagnetic field simulation and dynamic performance simulation was carried out, and the dynamic test rig was set up. The dynamic performances were investigated under different currents, frequencies, amplitudes and damper velocities. The experimental results show that the output damping forces can be continuously adjusted, which show a better dynamic performance. The maximum output damping force of the optimized MRD can reach 560 N, while the value of the initial MRD is only 253 N; the maximum adjustable range of the optimized MRD is 4.8, and the adjustable range of the initial MRD is only 3.7. The optimized MRD can achieve a better dynamic performance.