The invention discloses a copolymerized nano composite hydrogel for intelligent separation of cell sheets as well as a preparation method and application of the copolymerized nano composite hydrogel. The preparation method comprises the steps of: dispersing laponite in water, stirring to obtain homogenous and transparent dispersion, then sequentially adding polyethylene glycol macromonomer and N-isopropyl acrylamide monomer, uniformly stirring, removing oxygen, adding an initiator, transferring reaction liquid to a glass test tube and a reaction mold, sealing, and carrying out in-situ radicalpolymerization reaction at 15-25 DEG C to obtain a target product. The prepared copolymerized nano composite hydrogel has good mechanical performance and temperature sensitivity, and can be used for cell culture and rapid desorption of the cell sheets. The copolymerized nano composite hydrogel is suitable for cell growth, and can also realize rapid and automatic desorption of the cell sheets fromthe surface of the hydrogel by reducing the ambient temperature of the gel, thus tissue fibrosis and inflammation generation caused by use of biodegrable supports are avoided, and the damage to extracellular matrix and intercellular connection caused by use of trypsogen is avoided.