This study investigated the effects of typical anions such as Cl^-, NO₃^-, SO₄^2-, and PO₄^3- on the transport and deposition behaviors of titanium dioxide nanoparticles (nTiO₂) in iron oxide-coated sand under environmental related conditions (ionic strength and pH). In iron oxide-coated sand, the breakthrough curves and retained profiles of nTiO₂ were equivalent in NaCl, NaNO₃, and Na₂SO₄ solutions. However, under the same solution conditions (ionic strength and pH), the breakthrough curves of nTiO₂ in the NaH₂PO₄ solution were higher yet the retained profiles were lower relative to other three solutions. The results indicated that under the examined solution conditions (pH and ionic strength), Cl^-, NO₃^-, and SO₄^2- had similar effects on the transport of nTiO₂ in iron-coated sand, yet the presence of PO₄^3- could facilitate the transport of nTiO₂. The alteration of the surface properties of both nanoparticles and porous media, the change of particle sizes, as well as the competition of deposition sites on sand grain surfaces by PO₄^3- ions contributed to the increased nTiO₂ transport in iron oxide-coated sand in NaH₂PO₄ solutions.