To identify suitable plant species for the phytoremediation of arsenic-contaminated water and ensure the safety of people and animals, Vallisneria natans (Lour.) Hara was investigated for its ability to remove As from contaminated water. After 3 days of different As treatments (<2 mg/L), the As concentrations in the plants were high and the bioconcentration factor of V. natans exceeded 200 at 14 days. The As concentrations in all plants increased with time and increasing As concentration in the environment. As accumulation in the plant was significantly correlated with that in the environment. After exposure to different As treatments, V. natans showed good growth. This suggests that V. natans is highly tolerant to As and stable against environmental changes. Therefore, phytoremediation of arsenic-contaminated water can be achieved using V. natans and As accumulation in plants can reflect the level of As pollution in a region.