In this study, the effect of interaction between sodium dodecyl sulfonate (SDS) and titania nanoparticle on viscosity of water was investigated over a wide shear rate ranges of 10-200 s(-1) at different temperatures, respectively. It was found that adding SDS or TiO2 into water could both reduce the viscosity of the suspension. When they are added together, a synergistic effect could be clearly found. The resulting viscosity is much lower than the cases when they are added separately under certain temperature. The lubricating effect of the nanoparticle and analogous micelle were proposed to explain the phenomenon.