PBT fiber has good elasticity and disperse dye dyeability under atmospheric pressure, while maintaining the washable, wearable, crisp and dimensional stability of polyester, and the elasticity is between spandex and nylon. PBT filament modified by blending, copolymerization, compounding and other means can further improve its performance and reduce costs. It is mainly used for processing silk fabrics, yarn-dyed fabrics, warp knitted fabrics and decorative fabrics, and high-elastic yarns are used to make sportswear, elastic bandages, socks and elastic labor fabrics.PBT fiber has good elasticity and disperse dye dyeability under atmospheric pressure, while maintaining the washable, wearable, crisp and dimensional stability of polyester, and the elasticity is between spandex and nylon. PBT filament modified by blending, copolymerization, compounding and other means can further improve its performance and reduce costs. It is mainly used for processing silk fabrics, yarn-dyed fabrics, warp knitted fabrics and decorative fabrics, and high-elastic yarns are used to make sportswear, elastic bandages, socks and elastic labor fabrics.