Abstract. Injection molding is probably the most important method of processing of consumer and industrial goods, and is performed everywhere in the world. In this paper, Taguchi Methods was used to define the optimization of process parameter for an injection molding machine to produce a dumbbell product from High-density Polyethylene (HDPE) + natural fiber (Kenaf). Taguchi Methods with L9-3 4 approaches will be used in this work where two different formulation of material will be tested to find the best formulation and its parameter setting. Here, an orthogonal array (OA) and signal-to-noise (S/N) ratio are employed to analyze the effect of injection molding parameter. The significant of formulation and parameter setting from injection molding will be evaluated through the strength value of the specimen. Standard ISO R527-2 test method will be used. Results show that changes in the parameter setting will give different tensile strength value. The optimum parameter setting was set based on the S/N ratio. For each formulation, optimum parameter setting has been achieved by using highest mean S/N ratio and it can be calculated manually or by using Minitab software.