Surface roughness is normally regarded as an important criterion for assessing the quality of optic elements; surface roughness of a high-quality optic element is required to be less than RMS1nm. In this paper, a series of experiments has been conducted on the sample magnetorheological finishing machine by using self-prepared magnetorheological liquid as finishing liquid, to assess the removing efficiency of magnetorheological finishing. Optimization of technological parameters enables the authors to obtain a glass-ware with an ideal surface roughness of RMS0.56nm. Magnetorheological finishing (MRF) is an advanced technology for processing optic elements that has been developed in recent years. The technology polishes optic elements by using viscoplastic soft media produced by the MRF liquid under the variation of gradient magnetic field. Better than traditional polishing method in shape precision, surface roughness and inner surface destruction, MRF is an ideal technology for obtaining super-precision optic surface.