Arsenic (As) is considered as one of the most dangerous carcinogens in natural environment. In recent research, it has been reported that the extents of As accumulated in plants related to the plant species, soil characteristics and climate. Compared with paddy rice, the mechanism of the As uptake by upland crop is still unclear. In general, vegetables are grown in upland field which availablility of As in soil is low, so it is not easy to accumulate As in plants. However, due to water spinach can be planted in both flooding and upland field, which may cause the differences in As accumulation in plants between these two water managements. Therefore, the objective of the present study is to compare the distribution of As species and total As concentration in water spinach grown in As-contaminated soils with different water managements (flooding and upland conditions). In this study, two tested soils collected from Guandu(Gd) and Minsyong(Ms), which soil texture are clay and silt loam, respectively. The As concentration in Gd soils are 21 mg As kg⁻¹(GdL) and 139 mg As kg⁻¹(GdH), and those in Ms soils are 38 mg As kg⁻¹(MsL) and 100 mg As kg⁻¹(MsH). Besides, the contents of organic matter and free iron (Fe) oxide (DCB extractable) in Gd soils are higher than in Ms soils. The results showed that the arsenite (iAs^lll) was the dominant species in the soil pore water under two water managements, while the proportion of arsenate (iAs^V) in the upland field was slightly increased. Due to the higher contents of free Fe oxides in Gd soils, the amounts of Fe plaque on the root surface and biomass of the water spinach grown in Gd soils are higher than Ms soils. The results of plant analysis showed that the As concentration in plants grown in GdH soil was higher than other tested soils, and it also indicated the As concentrations in roots were higher than shoots. Inorganic As was the predominant species in water spinach, while the main As species in roots is iAs^lll, and the aboveground part is iAs^V. In addition, it was found that the proportion of iAs^V in plants grown in soil with upland condition was higher than flooding condition. Based on the results of this study, it suggests the As species in water spinach is highly related to those in soil pore water, and the As accumulation in edible parts are significantly decreased under upland condition.