Photochromic fiber as well as preparation method and application thereof

The invention provides a photochromic fiber as well as a preparation method and an application thereof. The photochromic fiber is a double-component composite fiber with a skin-core structure, wherein in a cross section of the double-component composite fiber with the skin-core structure, a skin layer and a core layer are in a concentric structure; the skin layer of the double-component composite fiber with the skin-core structure is made of low-smelting-point polyethylene terephthalate added with a phenoxy naphtho-naphthoquinone additive; the core layer is made of fiber-grade polyethylene terephthalate. The invention further provides the preparation method of the photochromic fiber. The photochromic fiber has good photochromism, heat stability, fatigue durability, short responding time, simple process and long service life, can serve as an anti-counterfeiting identification element for safe anti-counterfeiting and can also be used for garment materials and advertisements to increase the aesthetic feeling.