A method of indirect emission by nano-materials includes providing an infrared up-conversion phosphor 1 (weight ratio) and a long-wave ultraviolet phosphor 0.01-10 (weight ratio); treating both surfaces of the infrared up-conversion phosphor and the long-wave ultraviolet phosphor; mixing the infrared up-conversion phosphor and the long-wave ultraviolet phosphor; exciting the infrared up-conversion phosphor by a near-infrared laser with a wavelength of 980 mn to emit blue light as a secondary excitation lightsource; exciting the long-wave ultraviolet phosphor by the blue light to emit a visible light. Biological reactions can be conveniently detected by detecting the visible light.