Phytoremediation is actually a generic term for several says in which plants can be used to clean up contaminated soil, sludge, sediments, and ground water. The objectives of this research were to determine the amount and efficiency of total arsenic accumulation in various organs, the total arsenic removal efficiency arsenic in Colocasia esculenta (L.), Canna sp., Cyperus papyrus (L.), and Typha angustifolia (L.), and possibility of As(III) and As(V) transformation of four aquatic plants. A 4x3 Factorial designed in RCB was conducted with four aquatic plants and three treatments (control, As(III) and As(V) at 175 mg.kg⁻¹) at four harvested time 15 days, 30 days, 45 days and 60 days. The result showed that T. angustifolia had the highest arsenic accumulation followed by C. papyrus, Canna sp., and C. esculenta. All plants accumulated arsenic content in As(V) incorporated soil more than As(III). Each plant accumulated arsenic in difference organs. the highest accumulation organ of Canna sp. and T. angustifolia and were rhizome; however C. esculenta and C. papyrus was accumulated by maximum at root. Naturally, the oxidization reaction of As(III) to As(V) was always found, but the reduction reaction of As(V) to As(III) was not occurred in the submerged soil. The oxidized reaction increased from 33% to 91% at 15 and 60 days, respectively. However, transformation of both As(III) to As(V) and As(V) to As(III) were found in the plants, except the transformation of As(V) to As(III) in Canna sp. Percentage of As(V) transformation efficiency of all plants was at the maximum in 15 days, and then decreased to minimum at 60 days. Among the tested plants, C. papyrus was at the highest As(V) transformation efficiency followed by T. angustifolia, Canna sp., and C. esculenta. Leaf of C. papyrus was the highest organ of transformation efficiency, followed by culm, rhizome, and root.