This paper describes the advances in biological fundamental studies on artificial wetland wastewater treatment systems.In general,wetlands are the overlappd.parts of the land and water area, temporary or permanent shallow water is over the surfaces, and macrophytes are the dominant species.From the 1970s,artificial wetland wastewater treatment systems were developed from wetlands to enhance the wetlandsy water purifying function.Mediums, macrophytes,microorganisms are the basic elements and wastwater treatment is the main function of the artificial wetlands. At present, much more studies are carried out on the role of macrophytes in artificial wetlands, but fewer on microorganisms (including bacteria, actionomyces, fungus, protozoan, algae).Macrophytes uptake nutrients, adsorb and accumulate metals and other pernicious substances directly,also supply oxygen to the rhizosphere, establish diversified microcosms, increase and stabilish the hydraulic conductivity of the wetland.However, microorganisms are decomposers in wetland.The metabolic activities of microorganisms are the basic mechanisms of the organic content decomposing.During the microorganisms' metabolic activities,organic substances can be decomposed into terminal products which evaporate into the atmosphere, or nutrients which macrophytes and microorganisms can uptake, or substances which no or less pernicious to water area. Therefore,the studies on biological fundamental in artificial wetland must be developed, especially on microorganisms.Making systematic studies on the bacteria,actinomyces,fungus, protozoans and algae of the wetland are very useful for pursuing the mechanisms of wastewater treatment further and enhancing pollutant removal effects in artificial wetland.