The work aims to investigate mechanisms of influence and action of different process parameters including SiO2 abrasive solid content, polishing pad and down pressure on chemico-mechanical polishing (CMP) rate of zirconia ceramic. pH of silica sol was regulated to 10 by using sodium-type steady silica sol with particle size of 80 nm and sodium hydroxide solution (as pH regulator). CP-4 polisher was used to performzirconia ceramics polishing experiment and collect coefficient of friction, and viscosity tester was used to test viscosity of silica sol of different solid content, and scanning electron microscope (SEM) was used to analyze microstructure of two SUBA series polishing pads. When the solid content of silica sol was 37%, the material removal rate (MRR) was the quickest (54.3 nm/min), and COF was the minimum (0.1501). Continuous increase of solid content was accompanied by slight increase of COF which remained at around 0.1540. The polishing mechanism in which solid content of silica sol was over 37% was the result of hydromechanics, while the polishing mechanism in which solid content of silica sol was below 37% was the result of hydromechanics and mechanics. Compared with microstructure of SUBA600 polishing pad, that of SUBA800 polishing pad exhibited more and smaller pores. The MRR of SUBA800 was10 nm/min higher than that of SUBA600, since abundant pores have changed the contact mechanism of silica sol and polishing pads, increased shear force and COF, and intensified mechanical effect, which further accelerated polishing rate. The COF had no connection with down pressure. The MRR conformed to Preston equation when the down pressure was lower than 3.5 psi. For the CMP of zirconia ceramics, MRR is the quickest at the solid content of 37%. SUBA800 is more suitable for zirconia ceramics polishing than SUBA600. If the down pressure is below 3.5 psi, the MRR conforms to Preston equation and COF has no connection with down pressure.