Pure polyester yarn is made of polyester staple fiber by warp spinning, and the staple fiber has different categories. From the length, it can be divided into cotton fiber, the length is about 37 mm, there are medium and long fibers, the length is 51 mm-57 mm. mm, with hairy fibers, 75 mm-105 mm in length. In terms of thickness, there are fine denier fibers, which are around 1.5D, coarse denier fibers around 5D, and intermediate 3D fibers. Of course, there are finer fibers such as 1D, and even ultra-fine fibers such as 0.1-0.5D. 
　　The yarn is as fine as 50 to 60. It is better to use fine denier fibers for spinning, which is easy to spin evenly, has good evenness, and has less hairiness. If the fibers are longer, it can increase the cohesion and strength, and the spun yarn feels fine. , On the contrary, the rough denier yarn feels rough and has a better wool feel. and many more. When spinning polyester spun yarn, it is necessary to know how thick the fiber is, what the length is, and generally know where the staple fiber is produced. It has the characteristics of strong and durable, good elasticity, not easy to deform, corrosion resistance, insulation, crisp, easy to wash and quick dry.
　　Polyester fabric has high strength and elastic recovery, so it is durable and easy to iron. Polyester fabric, not deformed, has good wash and wear properties.
　　The major varieties of polyester are staple fiber, drawn yarn, textured yarn, decorative filament, industrial filament and various differentiated fibers.
　　1. According to physical properties: high and low elongation type, medium strength and medium elongation type, low strength and medium elongation type, high modulus type, high modulus type.
　　2. According to post-processing requirements: cotton type, wool type, linen type, silk type.
　　3. Distinguish by use: clothing, cotton, decorative, industrial.
　　4. Differentiated by function: cationic dyeable, hygroscopic, flame retardant, colored, anti-pilling, antistatic.
　　5. According to the fiber cross section: special-shaped wire, hollow wire.