The invention discloses a construction method for an enclosure structure unit of a water-area ecological breeding pasture as well as the enclosure structure unit and application thereof. The enclosure structure unit comprises at least two concrete tubular piles which are mutually spaced and fixed in a water area, and a grating net connected between every two concrete tubular piles, wherein the construction of each concrete tubular pile is combined with a specific outer retaining wall indwelling layer or an outer retaining wall sleeve, and a concrete cast-in-place method is adopted, so that the concrete tubular pile is quickly formed. The enclosure structure unit is utilized to enclose the water area into an ecological breeding pasture which can perform water exchange with the outside. The construction method for the enclosure structure unit of the water-area ecological breeding pasture as well as the enclosure structure unit and application have the advantages that through the technology, an enclosure structure unit which is strong in wind and wave resistance and efficient and fast in construction can be processed, thereby further forming a water-area ecological breeding pasture, which is conducive to promoting development and utilization of water area resources, especially the marine resources, and economic and social development.