The invention discloses a photochromic 
polyester fiber with a sheath-core structure, which comprises a sheath layer and a core layer, wherein the 
mass ratio of the sheath layer to the core layer is 2:8 to 4:6; the sheath layer is 
polyester resin, and the core layer comprises core layer fibers and color master batch for coloring the core layer fibers, wherein the 
mass percentage of the color 
masterbatch to the core layer is 3% to 10%; the color master batch comprises, by weight, 0-90 parts of a carrier, 1-30 parts of photochromic 
powder, 0-20 parts of a dye, 0.3-1.5 parts of a heat stabilizer,0.2-1 part of an 
antioxidant, and 0.5-1.5 parts of a dispersion aid. According to the photochromic 
polyester fiber with the sheath-core structure, the color master batch is added into the core layer,so that the original solution coloring of the polyester 
fiber is achieved, the production cost is reduced, and the environmental 
pollution is reduced; moreover, since the color master batch containsphotochromic 
powder, the polyester fiber gains photochromic characteristics; and the photochromic effect is long, so that the use requirement is met.