Abstract: By using plot investigation and system simulation methods, and taking a typical complex wetland ecosystem in Liaodong Bay as research object, the organic pollutants purification efficiency of the ecological units was analyzed comprehensively and a pollutants purification capacity estimation model was built correspondingly. Furthermore, an optimal design to the wetland ecosystem based on its DEM (digital elevation model) information was made. The results indicated that the purification ability for COD_Cr, BOD₅ and petroleum were different in each ecological units, which led to different purification loading rate of systems with various components and structures. The original COD_Cr purification capacity and the removal loading of COD_Cr in the study area were 188.9 kg·d^-1 and 284 g·m^-2·d^-1, respectively, while they were up to 313.3 kg·d^-1 and 4.72 g·m^-2·d^-1 after the optimal ecological design based on the DEM information, with the purification efficiency being enhanced by nearly 20%.

Key words: complex ecosystem, purification ability, digital elevation model (DEM), ecological design, peanut, biomass, nutrient accumulation, ecological adaptability, comprehensive eva-luation.