Abstract: Mire as an ecosystem, usually is considered as aquatic ecosystem, or terrestrial ecosystem. The author thinks that mire is a special ecosystem between these two ecosystems, and proposes the new concept that mire is a natural ecosystem with transitional nature of semi-land and semi-water formed by water and land interaction. The paper discusses the nature of mire ecosystem, the exploitation and utilization and ecological construction of mire in four parts. 1. Whereas mire ecosystem commonly occurs and exists in section or belts joined by water and land, mire can evolve from water-body or land. Except mire, other ecosystem cannot evolve from water or land, So the distri bution and growth of mire have the features of both water and land. 2. Water is the precondition and environmental factor of mire formation. Mire contains a lot of water, but it is not a real water-body.The paper discusses the hydrological regime and transition of ecological environment in terms of the existing and moving forms of water, water quality and hydrochemistry. 3. Ecological group is classified based on the comrosition and morphologicai-ecologieal feature of plant community and animal community. Some typical plants and animals in mires possess amphibious and transitional in order to adapt themselves to the special habitat of semi-water and semi-land. 4. There are various of types mire, so mire utilization are different, must depend on their features. Dike-pond system is a particular artificial ecosystem with water-land interaction. It makes good use of water and land resources. Building artificial sterero water-land system of planting and cultivating is an excellent successful experience in ecological construction of mire. According to the principile of dike-pond system, varionus patterns have been created in China.