Milling vibration will greatly affect the milling accuracy and surface quality of thin-walled workpiece. Considering that the characteristics of instant curing high-efficiently under the action of magnetic field and can be recycled without wasted of magnetorheological fluid (MRF), a MRF composite clamping to suppress milling vibration is proposed in this paper. Based on the fluid–solid coupling dynamics theory, the dynamics modal of the MRF clamping is established. On this basis, considering the influences of the filling volume of MRF to processing vibration, the suppression effect of MRF on milling vibration is analyzed in time domain and frequency domain, respectively. A series of simulations and experiments are carried out on typical annular thin-walled workpiece, the result shows that the maximum increase of natural frequency of thin-walled workpiece is 53.1% while filling with MRF, and Ra, Rz, Rq decreased by 36.1%, 14.8% and 16.7%, respectively. The consequence verified the reliability and effectiveness of the proposed method in the whole milling process.