the stability of TiO2 nanoparticles dispersion system was got by dodecyl sodium alginate (NaAlg-Dode) adsorbing on the TiO2 nanoparticles. The particles size, zeta potential and rheological properties of suspension system were measured by means of Fourier transform infrared spectrometer (FTIR), Dynamic light scattering (DLS) and Rheometer. The influence of NaAlg-Dode on the aggregation behavior of TiO2 nanoparticles in aqueous solution and rheological property were researched at various pH values. Experimental results showed that NaAlg-Dode was conducive to the stability of TiO2 nanoparticles dispersion system within the scope of pH=4~8. The average size of TiO2 particles from 2.5祄 down to around 500 nm and the surface Zeta potential of particles reduced from 0 mV to about -40mV at pH=6.3.At the same time the shear stress of TiO2 nanoparticles dispersion system increased gradually with the addition of NaAlg-Dode, which suggested that the interaction between particles enhanced. Therefore, the stable mechanism of TiO2 nanoparticles dispersion system by NaAlg-Dode improving： NaAlg-Dode molecules was able to promote particles stable disperse in aqueous solution via changing the zeta potential and space steric of TiO2 by electrostatic interactions, hydrogen bonding and hydrophobic function.