The tideland is a kind of special environment system, which can mirror influences from human being"s activities, and the humus in the sediments will affect the moving laws of heavy metals. with the tideland sediments as the object of the study, the authors extracted the humic acid and tested the adsorption of Cr(Ⅲ) in water solution. The result shows that 0.1g humic acid can reach saturation adsorption under the anditions of room temperature (20～25℃), pH 4～5 and Cr(Ⅲ) concentration 800 μg/mL. The adsorption capacity is 6.5mg/g. The adsorption is fitted well to the Langmuir isotherm equation.