The invention discloses a preparation method of water-based photoresponse nano gel, and relates to the technical field of macromolecule materials. The method comprises the following steps that firstly, a cross-linking agent needed by synthesis of the nano gel is prepared, and then the water-based photoresponse nano gel is prepared through a reversible addition-breakage chain transfer free radicalpolymerization method; the invention further discloses the water-based photoresponse nano gel prepared through the preparation method and application thereof; the prepared nano gel has the advantagesthat the prepared nano gel has the good photoresponse and the loading capability, and medicine loading and photoresponse release of the nano gel are facilitated; the prepared water-based photoresponsenano gel has the excellent biocompatibility, and the wide application prospect is achieved in the field of medicine release.