For the purpose of achieving the industrial requirement of efficient and high precision polishing of zirconia ceramics, nanodiamond@SiO2 abrasives were synthesized by a simple method using tetraethyl orthosilicate as raw materials. As observed in the transmission electron microscopy results, the composite abrasives showed a homogeneous and dense silica coating layer. It was confirmed by Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy that the composite abrasives have a core-shell structure with a diamond core and a silica shell. According to the Zeta potential analysis, the dispersion stability of composite particles was improved compared to that of the pure nanodiamond particles. The chemical mechanical polishing results show that the polishing performances of composite abrasives on zirconia ceramics are better than that of the pure nanodiamond abrasives. The material removal rate of the composite particles is 2.184 µm/h, and the surface roughness of the polished zirconia ceramics is 1.055 nm, which was 140% higher and 89% lower than that of pure nanodiamond abrasives, respectively. Furthermore, the polishing mechanism was explored by X-ray photoelectron spectroscopy, friction coefficient meter, and dynamic contact angle test.