In this paper, the chemical character of NiP substrate of computer disk is analyzed, the CMP kinetics processing is discussed to indicate that the chemical reaction is the slowest and the control process. By analyzing essentiality of slurry on NiP film CMP, it is indicated that the chemical component of slurry acts the important role in CMP. New type of alkali slurry for NiP substrate was prepared and its CMP mechanism is studied with alkali slurry. Strong complexation of complex agent improved selectivity of concave area and convex area to get higher removal rate. Low roughness is realized with small size and low hardness silica sol as abrasive.