Slurry preparation is of paramount importance in chemical mechanical planarization (CMP) process. It couples the combination effects of chemical and mechanical ones. In this paper, the characteristics of the slurry particles used in CMP are firstly modeled, which includes the size and the concentration with primary priority. And then, the model is validated by experiments during hard disk wafer polishing. The slurry prepared contributes to a high quality hard disk surface processed with CMP, which leads to low waviness Wa and roughness Ra with suitable material removal rate (MRR) as well. The study will surely lay a feasible foundation to the CMP mechanism.