The invention relates to a seaweed chemical sodium alginate solution double-calcium calcification extraction and calcified wastewater recycling process, which belongs to the technical field of environmental protection and chemical engineering. The process is improved based on a traditional seaweed chemical calcification process, and adopts CaCl2 and Ca(OH)2 as a mixed calcification agent, wherein the Ca(OH)2 mainly ensures complete calcification and maintains the concentration of Ca<2+> in a water body, so that not only is a calcification effect ensured, but also the calcification cost is reduced; remaining calcium in calcified wastewater produced after calcification is mainly the Ca(OH)2, most free Ca<2+> can be transformed into CaCO3 deposition so as to be removed with low cost under the condition of introducing CO2, meanwhile, the ion concentration of the water body is reduced, and the wastewater can be used as diluted water for recycling.