This paper presents an optimization of the water based TiO2 nanofluid preparation process for thermal conductivity and zeta potential by using Taguchi method for single-objective and Grey relation analyses for multi-objective optimization. Stirring time, sonication time, mass ratio of surfactant to particle and sonication power are selected as optimization factors to obtain higher thermal conductivity and zeta potential. Sixteen different nanofluid samples having various preparation parameters are determined and prepared within the scope of the Taguchi method. The thermal conductivity and the zeta potential of the samples are measured under constant temperature of 20℃. The contribution levels of the considered parameters on the thermal conductivity and the zeta potential are respectively ordered as the surfactant to particle ratio, the sonication time, the sonication power and the stirring time, by using analysis of variance (ANOVA). A confirmation test is carried out with optimized parameters and also ensured the confidence of the method.