In order to characterize the adsorption behavior of arsenic (As5+) on hydromorphic paddy soil derived from 5 mother materials(yellow clayey soil, alluvial sandy soil, granitic sandy soil, purple clayey soil, reddish yellow clayey soil), adsorption isotherm experiment was conducted with soil sampled from leached layer(horizon A, 0-25 cm) and illuvial layer(horizon B, ＞25-50 cm) of these paddy soil. The results indicated that the adsorption of As5+could perfectly fitted by Langmuir, Freundlich and Temkin adsorption isotherm. Compared the maximum adsorption As(Xm) and the max buffering capacity(MBC) obtained from the Langmuir equation, it showed that the Xm of horizon B was 1.2 times of horizon A, and the MBC of horizon B was 6.3 times of horizon A, and the variation coefficient of horizon B was bigger than horizon A. The yellow clayey soil had the biggest Xm and MBC, followed by alluvial sandy soil, then reddish yellow clayey soil and granitic sandy soil. When the soil pH were 4.97 to 6.68, the Xm were significantly correlated with the contents of Fe and free iron oxide, and there was a significant negative correlation between MBC and the contents of soil organic matter in soil. Nearly 86% of the variability in arsenate adsorption on the soil could be described by total Fe contents in soil. There was a great difference in arsenate adsorption capacity and buffering capacity of 5 hydromorphic paddy soils. The total iron and organic matter content of the soil were the main soil factors affecting the maximum adsorption capacity and maximum buffer capacity of soil, respectively.