The invention belongs to the field of preparation and application of nano materials, and discloses a composite nano material capable of exciting upconversion steady persistence through near-infrared light, and preparation method and application of the composite nano material. By utilizing the composite nano material disclosed by the invention, the situation that nanoparticles are excited by near-infrared wavelength light to generate steady persistence luminescence is realized. The composite nano material is of a special composition structure which is obtained through combination of an upconversion nano material and a steady persistence nano material. According to the composite nano material disclosed by the invention, the situation that visual light emitted the upconverision nano material after near-infrared light is absorbed by the upconversion nano material is matched with absorbed light of the steady persistence nano material, i.e., the visual light emitted by the upconversion nano material is absorbed by the steady persistence nano material, so that light emitting of the steady persistence nano material is realized, the generation of steady persistence luminescence under the exciting of the near-infrared light is realized, the problems of a traditional steady persistence nano probe that the penetrating power of short-wavelength laser is weak, materials in a living organism cannot be excited, and the like are overcome, and deep optical imaging with continuous detection, high SNR (Signal to Noise Ratio) and a simple detecting device and without background exciting light, tissue autofluorescence, and a light filter is realized.