The invention discloses a preparation method of noctilucent fibers capable of emitting 
red light in 
darkness. The preparation method comprises the following steps: mixing 2-hydroxybenzaldehyde with 3-hydroxyl-N,N-
dimethylaniline which can be dissolved in water to obtain a mixture, heating the mixture, mixing the mixture with 
anhydrous zinc chloride and 
sulfuric acid to obtain a mixture I, and carrying out the reaction on the mixture I to obtain a light conversion agent; mixing the light conversion agent with SrAl2O4:Eu<2+>, Dy<3+> and a 
fiber forming 
polymer base material to obtain a mixture II, 
smelting the mixture II, and granulating to obtain noctilucent particles for 
spinning; and 
drying the noctilucent particles, then 
smelting the noctilucent particles and 
spinning to obtain the noctilucent fibers. The 
red light emitted by the noctilucent fibers prepared by adopting the preparation method can be maintained for more than ten hours, the highest luminance can reach 3.0cd / m<2>, the emitted 
red light is one of three basic colors, and the noctilucent fibers can be compounded with one or two of 
blue light noctilucent fibers and 
green light noctilucent fibers to prepare luminous colorful noctilucent fibers, so that the important significance can be realized.