To inquiry the factors of removal efficiency of different-concentration TiO₂ NPs by coagulation processes and the difference between different-concentration TiO₂ NPs and turbidity in removal performance. This paper investigated the impact of sonication pretreatment and surfactant (LAS) on the stability of TiO₂ nanoparticles (NPs) in solution firstly, for getting dispersion stabilized suspension. We also studied the effect of dosage of coagulant (PAC) on different-concentration TiO₂ NPs based on jar test, and the dependence of surface zeta potential on pH.The results demonstrated that the best stability of TiO₂ NPs was obtained at sonication power of 250 W for 10 min under LAS concentration of 20 mg／L. The removal of TiO₂ NPs and turbidity exhibited the similar trends under various coagulant concentrations. The optimum coagulation dosage was 3 mg／L at initial TiO₂ NPs concentration of 0.5,1 and 2 mg／L, which corresponded to removing efficiency of TiO₂ NPs and turbidity of 46.2％, 60.2％, 68.8％ and 23.2％, 43.6％, 47.6％ respectively. The optimum coagulation dosage of 4 mg／L for initial TiO₂ NPs concentration of 5 mg／L resulted in removal of TiO₂ NPs and turbidity of 77.6％ and 54.1％. The pH value was found to have significant impact to Zeta potential, and then has influence on the removal effect of TiO₂ NP.