The invention discloses preparation and application of multi-wavelength regulated optical switch fluorescent polymer nanoparticles. The multi-wavelength regulated optical switch fluorescent polymer nanoparticles are prepared through a one-step miniemulsion polymerization method, wherein a fluorescence resonance energy transfer principle (FRET) is adopted, andmethyl methacrylate (MMA), an optical switch fluorescent dye (SP-PDI-DA) and photochromic compound diarylethylene (DTE-BA) are taken as main raw materials. The nanoparticles have the characteristics of a fast and reversible fluorescent switch under the irradiation of ultraviolet light and visible light. Compared with existing optical switch fluorescent polymer nanoparticles, the obtained optical switch fluorescent polymer nanoparticleshave the advantages of multilayer optical switch capability, stable water dispersibility, small particle size, low cytotoxicity and simple preparation method, are suitable for amplification production and practical application, and have great application prospects in the technical fields of information encryption, display materials and the like.