The reed is often observed along the natural coast. it is known by its ability and capacity of trapping particles, decompositing organics and consuming nutrient pollutants from its roots. Field observations to the wild salty marsh are conducted to survey the ecological role and suitable condition of its growth. Cultivation study is also conducted to grasp the reaction to the salt water. The application of the ability to the water and sediment clarification will be made after the study of the physiology and ecological play to the waste water treatment and improvement of the environment at the artificial marsh.