The present development of chemical fibers in the world has been aimed at several fundamental domains arising from the rapidly expanding knowledge in the chemistry and technology of polimer materials. So this development is providing the textile industry greater flexibility in using varying grades and conditions of fiber, creating more desirable blends. As a result blending of fibers improve their processability and properties of fibers. Because it is possible then benefit from both of the fiber properties of blend. Also blending of expensive and high quality fibers with other standard quality fibers provide reducing costs and this will give the chance to the mill competing with arising prices. In this article the usage of fiber blends and optimum pretreatment conditions of the blends are reviewed.