Abstract: In the study, the untreated and potassium chlorate, (KClO3) treated micro sized Date Palm Petiole Fiber, (DPPF) were used to produce natural fiber/HDPE composites by injection molding machine. DPPF was characterized to determine their chemical compositions in terms of cellulose, hemicellulose and lignin. Central Composite Design (CCD) tool of RSM was applied for optimization processes. Analyses of the results showed that cellulose content is, hemicelluloses and lignin. Chemical treatment of the fibers modified and enhanced properties of the fibers.