The invention discloses a visible-radiation-based water-soluble monomer atom transfer radical polymerization (ATRP) method. Particularly, the method comprises the following steps: 1) preparing a catalyst/ligand complex solution; 2) carrying out ATRP in an n-heptane/ethanol mixed solvent; 3) after the polymerization finishes, adding water to induce the solution to be stratified, and carrying out treatment to obtain a polymer; and 4) adding a new monomer, an initiator and a two-component visible photoinitiator into the recovered catalyst/ligand complex to carry out the next polymerization. The ATRP reaction is carried out under the mild efficient visible radiation, thereby implementing superhigh monomer conversion rate (greater than 95%) within a wider wavelength range, and obtaining the high-controllability polymer. The method can recycle the catalyst, is simple to operate, and has the advantages of high designability, lower cost, time saving and labor saving.