By using the principles and methods of system engineering, components of an ecosystem can be readjusted in terms of their space position, time order and numerical proportion so that more material exchange, energy flow and information transmission may result and thus an ecosystem of orderly structure, effective function and high productivity can be artificially secured. Projects that deal with such work are called ecosystem engineering.Nutritional materials and energy existing in the environment are external and those consumed by organisms in their physiological metabolism are of the internals. Life process of organisms is to convert external materials and energy into internal materials and energy and the internals into the externals. These input and output exchanges between a bio-system and its a biotic surroundings can be termed dynamic movement of "eco-boundary" which is characterized by the action of "selctive filtra; tion" and regulated by the adaptative vitality of organisms and the fitness of envis ronmental conditions. Since an eco-boundary system governs the fundamental relationship between organisms and the surroundings where they inhabit, it is essential to understand the characteristics and functions of eco-boundary systems and their relations to entropy and information transmission when constructing an artificial ecosystem or reforming a natural ecosystem.