The growing application of Nickel-Titanium (NiTi) alloy in aerospace and medical industries has spurred research into ultra-precision polishing. NiTi's corrosion resistance and hardness make achieving an atomic-level surface finish through chemical mechanical polishing difficult. A new polishing slurry containing hydrogen peroxide (H 2O 2), composite abrasives (silica sol and Eu 2O 3), mandelic acid (MA) and malic acid (MalA) was developed. A surface roughness (Sa) of 0.141   nm was achieved over an area of 20 × 20 μm², which was the lowest value reported. Material characterization confirmed the strong oxidizing nature of the slurry. Moreover, the composite abrasives functioned as efficient catalysts and exhibited excellent dispersion stability. The study shows that the slurry promotes the mechanical removal of surface chemical layers through synergistic abrasive action, ultimately producing an atomically smooth surface on NiTi alloys. This result demonstrates great application potential in ultra-precision manufacturing.