On the basis of the risk assessment of Cadmium (Cd) and Arsenic (As) pollution in Nanjishan Wetland soil and Artemisia selengensis in March 2012, the effects of water conditions on the physicochemical properties of wetland soil, the morphology of As and Cd, and the heavy metal enrichment capacity of Artemisia selengensis in the Lake Poyang were studied by pot experiments. Results showed that the content of Cd in soil exceeded the standard values, suggesting kind of ecological risk. The As concentrations in the stems of Artemisia selengensis is up to the limit standard of food pollution, which raised the risk of food consumption. The enrichment abilities of Cd and As by Artemisia selengensis were affected by the soil water environment. The increasing of water would increase soil pH and organic matter content, which inhibited the enrichment of Artemisia selengensis toward Cd while promoted the enrichment of As. The results of the linear regression showed that there was a significant positive correlation between the effective content of As in soil and the As concentrations in Artemisia selengensis, which could be used to evaluate the As enrichment characteristics of Artemisia selengensis. However, no significant correlation was found between the effective content of Cd in soil and the Cd concentrations in Artemisia selengensis. Combined with the condition of Cd and As pollution in the regional soil, the suitable control of the alternation of wet and dry or water shortage water conditions could reduce the concentrations of Cd in wetland plants such as Artemisia selengensis, the suitable control of waterflooding water condition could reduce the effective contents of Cd and As in soil.