Natural fibers as reinforced polymer composites have recently been the center of attention among researchers. Surface modifications and variations in the fiber diameters are major factors that influence the fiber adhesion performance inside the matrix. Experiments have been performed to further the development of natural fiber reinforced polymers as a replacement for glass fibers. In the present research, date palm fibers (DPFs) with three different size ranges of diameters (800-600, 600-400, and $400-200{mu}m$) and the influence of alkali treatment on their characteristics have been investigated. Morphology observations (SEM), EDS density mapping (quantitative elemental analysis), X-RD, and FTIR spectroscopy of treated and untreated fibers were carried out. In addition, the tensile properties of a single fiber and composites consisting of fibers/epoxy with discontinuous random oriented short fibers both with and without chemical modification were studied. The results showed that DPFs are amenable to chemical modification particularly in the fine fiber case. It was found that the ultimate tensile strength and percentage elongation of a single fiber after alkali treatment increased by 57% and 24.7 %, respectively. Because alkali treatment of the DPFs was able to provide a good adhesion within the matrix, the tensile strength, elastic modulus and the fiber-matrix interaction of the composite were improved. Collectively, the addition of the proposed DPFs may open a new avenue for the exploitation of this natural cheap material to produce a green composite.