Abstract: Chemical mechanical polishing is a key process in the manufacturing of semiconductor and optical devices, and its performance is highly dependent on the physicochemical properties of the abrasives. Cerium oxide (CeO₂) owing to its excellent chemical activity and suitable mechanical strength, has become one of the mainstream abrasives for polishing silica-based materials. However, CeO₂ abrasives prepared by traditional methods often suffer from issues such as uneven particle size and low surface activity, limiting further improvement in polishing performance. In this study, CeO₂ nanoparticles were synthesized via the molten salt method at different temperatures (750 ℃, 800 ℃, 850 ℃), and the effects of preparation temperature on their phase structure, morphology, surface chemical state, and polishing performance were systematically investigated. The results show that as the temperature increases, particle size increases and crystallinity improves. Under the 800℃ condition, the Ce³⁺ content and oxygen vacancy concentration were the highest, at 21.13% and 13.32%, respectively. Meanwhile, the CeO₂ abrasives prepared under this condition demonstrated optimal polishing performance, achieving atomic-level surface roughness on a SiO₂ substrate after polishing. This study offers both process guidance and theoretical support for the controlled synthesis of high-performance CeO₂ abrasives aimed at atomic-level wafer surface processing.