Chemical mechanical polishing (CMP) has been a widely applied process for hard disk substrates with nickel–phosphorous (Ni–P) plated. In this paper, the effects of abrasive and surfactant on the polishing performance of hard disk substrates using prepared colloidal silica-based alkaline slurry were investigated. The experimental results indicate that the material removal rate (MRR) strongly depends on the abrasive concentration and nonionic surfactant have little influence on the material removal rate. Under the testing conditions, smaller SiO2, moderate SiO2 concentration and higher surfactant concentration can obtain high surface quality in the prepared slurry. These results have been explained by which the abrasive particles move through the cover layer caused by surfactant adsorption on the disk substrates surface being polished.