The natural fiber prepared from the banana stem is a potential alternative reinforcer to enhance the mechanical properties of composite materials. The fibers have been extracted successfully from various species of banana, that are Abaca (Musa textilis), Kepok (Musa acuminata) and Klutuk (Musa balbisiana). The fiber extraction was undergone an alkaline treatment, i.e., by immersion in 0.5% NaOH, and then in 50% acetic acid, each for an hour. Characterization of fiber with different treatment immersion mediums for functional groups using FTIR. It shows a reduction of concentration lignin and hemicellulose content in the fibers. Furthermore, from a fiber tensile test, the tensile strength of the fibers are 1106.7, 398, and 432.5 MPa for each kind fiber banana. The Abaca's fiber is shown to have a superior mechanical property, which will be competitive for a composite reinforcer.