This scientific work concerns the study of injection parameters for the manufacture of HDPE composites with wood fibers. The mass proportions of wood fibers range from 10 to 40%. Thus, the parameters of injection such as Pressure and temperature of injection, cooling time were varied and the influence of each parameter during the process of injection is determined using the experimental design L4 of Taguchi. Bending, tensile, Izod and impact samples were fabricated and the respective tests were performed. The results of this study have shown that the Young and flexural moduli, the maximum stress, the energies absorbed at break by variation of the injection parameters are better than those obtained by thermo compression. In addition, the increase in fiber content in the composite leads to a very substantial increase in the modules. Among the injection parameters studied (injection pressure and temperature, cooling time), the injection temperature is the most determining parameter to control during the injection process