Kinetics and distributions of alkaline phosphatase in water, natural and filtered (<0.45μm), coupled with sediment, in constructed wetland (12.5m×9.5m)inhabited by Potamogeton crispus L., Alternanthear philoxeroides Griseb.and Spirodela polyrhiza L.respectively, were determined.The plants inactivated the enzyme, in kinetic sense, in surficial sediment and water, depending on species.The inactivation was most obvious in unfiltered water samples implying an enzymatic mechanism explaining the plant-algae interaction.In sediments covered by rooted plants, the enzymatic activity was lower in surficial layers, leading a nutrient retention and water quality amelioration, but significantly higher in the relatively deeper layers.The complexity of subsurface in wetland sediment deserves further study, which is of great theoretical and practical significance.