The invention relates to a preparation method of photochromic fabric. The preparation method comprises the following steps: immersing fabric into reduction solution, stirring, washing and drying, so as to obtain pretreatment fabric; dissolving a photochromic material into a solvent to obtain solution, immersing the pretreatment fabric into the solution, adding triethylamine, heating and stirring, washing and drying, so as to obtain the photochromic fabric. The photochromic fabric prepared by the invention can produce an excellent photochromic effect mainly by ultraviolet irradiation; in a dark environment, the color is enabled to get back to the original form in a reverse direction due to the change; in addition, a click chemistry reaction is mild in conditions, high in yield of products, less in side reaction and small in environmental pollution. The photochromic fabric prepared by the method has excellent photochromic property and good fatigue resistance, is easily available in raw materials and simple and convenient in pretreatment and is washable; in addition, the preparation processes are simple, and the cost is low.