The work aims to develop a high efficiency and quality ultra-smooth surface polishing technique for zirconia ceramic. The zirconia ceramic was processed in the method of magnetorheological finishing. A self-developed magnetorheological polishing device was used, and magnetorheological polishing fluids containing diamond abrasives were prepared. A single-factor experiment was designed to study the effects of main process parameters including polishing time, working gap, workpiece speed and polishing trough speed on magnetorheological polishing properties of zirconia ceramics. The material removal rate (MRR) and surface roughness was analyzed using precision electronic balances and white light interferometry profiler, respectively. Provided with the process parameters as follows: working gap of 1.4 mm, workpiece speed of 100 r/min and trough speed of 25 r/min, the workpiece surface roughness Ra decreased over time before reaching saturation, and finally reached saturation value 0.7 nm after 30 min polishing. As polishing time advanced, surface roughness was no longer improved anymore. The MRR of zirconia ceramics increased with the increase of workpiece speed and trough speed, and decreased with the increase of working gap. The MRR could be up to 1.03 mg/min at workpiece speed of 300 r/min, 0.80 mg/min at trough speed of 25 r/min, and 0.77 mg/min at working gap of 1.0 mm. Higher MRR of zirconia ceramic and nanoscale surface roughness can be improved in the method of magnetorheological finishing based on large polishing tool, and efficient ultra-smooth surface processing of the zirconia ceramic can be achieved.