Strength and elongation polyester filter cloth is not only because of its molecular structure, stretching and heat treatment process and fiber spinning process is closely related to the Strength and elongation . After stretching, polyester filter cloth macromolecular chain according to a certain direction, to improve the degree of orientation, so that it can even bear the external force, the strength increase. The fracture strength of polyester fabric usually short fibers is about 0.27-0.66cN/tex, the elongation at break in between 25%-50%. In the heat treatment under the suitable conditions, the higher the degree of stretching polyester filter cloth in spinning process, then the fiber orientation degree is high, the tensile strength of the fiber was increased, while the elongation at break is lower; on the contrary, is likely to be low strength and high elongation fiber. The change of tensile and heat treatment conditions, can be made of high strength and low elongation and low strength and high elongation of different kinds of fiber. Figure 5-7 the strength elongation curve of fiber.