The invention belongs to protective fishery field, which in detail relates to two-cycle water treating system for industrialized fish culturing, with main characteristics being: internal recycle pool structure of various shape taking square outside and round inside as representation, cultivating fish in circular pool, the quadrangle outside pool is biological filter; water and pollution discharging pipe are equipped in bottom of pool; the mating outside circular system comprises drainage ditch, out biological filter and artificial wet land, feed ditch, pollution collecting tank; special air raising pump of U shape, high effective aeration, water raising cycle; the artificial wet land and out biological filter are combined together, depositing, filtering, adsorption, bacteria degradation, adsorption by aquatic plant and animal and cleaning water body high effectively; constructing open water inlet and outlet pitch which also used as biological filter by using fish pond to realize omni-bearing restore of cultivating wastewater. The invention is characterized by less equipment investment, low energy consumption, safe and reliable operation, convenient management and maintenance, outstanding ecological, economical and social benefit, low production cost and increased quantity and quality.