With orthogonal tests of three levels of Chemical Oxygen Demand(COD), Total Nitrogen(TN) and Total Phosphorus(TP) in artificial nutrient-rich wastewater at different ambient temperatures, the optimum growth conditions of five species of duckweed collected from the Yangtze River Delta were studied. The results could be applied to superior duckweed species selection, with which nutrient-rich wastewater treatment could be renovated in the Yangtze River Delta.