Magnetorheological(MR) fluids are a kind of dispersion system. Through the study on the stability of dispersed system and the actual needs of magnetorheological finishing (MRF), the components of a water-based MR polishing fluids are determined, which are suitable for optical manufacturing in this paper. The initial viscosity of the MR polishing fluids is only 0.2 Pa·s. The yield shear stress of this MR fluid is 42.5 kPa via magnetic rheometer test under the shear rate of 1 s-1 and magnetic field intensity of 0.35 T. Polishing experiments are carried out on K9 glass and silicon with the MR polishing fluids. The experimental results show that the relative changes of removal function peak removal rate are 0.15% and 0.22%, and volume removal rate are 1% and 0.88% for K9 glass and silicon respectively in 2 h continuous polishing. The peak removal rate of removal function reaches 4.83 μm/min for K9 glass and 1.376 μm/min for silicon. The results prove that the MR polishing fluids has a good stability and high removal efficiency which ensure that the polished material will be fast removed and has convergent efficiently by MRF.