The natural fiber-reinforced polymer composite is capturing view in many industrial applications like automotives and many other human centric oriented frugal innovation products and fundamental research. Fiber reinforced polymer composites have a wide variety of applications as a class of structural materials because of their advantages such as ease of fabrication, relatively low cost of production & superior strength as compared to neat polymer resins. The fiber which serves as a reinforcement in polymers may be either synthetic or natural. Although synthetic fibers such as glass, carbon, nylon, polyester etc [1]. Possess high specific strength; their fields of applications are limited because of their higher costs of production. Recently, there is an increasing interest in hybrid composites that are made by reinforcement of two or more different types of fibers in a single matrix, because these materials attain a range of properties that cannot be obtained with a particular kind of reinforcement. Further, material costs can be reduced by careful selection of reinforcing fibers. Natural fibers have been proven substitute to synthetic fiber in transportation domain such as automobiles, railway coaches and aerospace because of their low thermal expansion, high tensile strength, high strength to weight ratio. Other applications include military, building, packaging, consumer products and construction industries for ceiling paneling, partition boards [2]. Currently, the Mechanical treatments of the fibers are carried out as they further enhance the properties of the composites. This paper deals with review of fiber treatment on mechanical properties of different natural fibers reinforced polymer composites.