The force of the polyamide fiber is the strongest among all the fibers; the tenacity is 4-5.3CNdtex, and the elongation is 18%-45%. The recovering ability is above 90% when elongation is around 10%. Its anti-abrasion is 10 times of the cotton fiber, and 50 times of viscose fiber. Wearability occupies the first place in various kinds of fibers, so it is an ideal material for rubber automobile tire making. Polyamide fiber has great alkali proof, but can only stand for weak acid. Under the condition of Nao (10% ), 95℃, 16 hours, the tenacity almost lose nothing. But polyamide fiber can not stand for sunlight. It will easily become fragile and change color, so polyamide fabric should not be exposed under the sunlight for a long time. It is used in the ceramics factory, the pharmaceutical factory, foodstuff industry, and metallurgy, etc., and it is more suitable for the rubber trade.