In this paper, high density polyethylene (HDPE)/wood flour (WF) composite foams were prepared by using an intermeshing co-rotating twin screw extruder followed by an injection molding. Experimental design based on Taguchi method was applied to investigate the effects of "concentrations and types of chemical foaming agent (CFA)", "HDPE melt flow index (MFI)" and "WF content" on, density, mechanical properties and morphological structure of HDPE/WF composite foams. The analysis of variance (ANOVA) demonstrated that MFI, CFA concentration, CFA type and WF contents can significantly affect the optimized mechanical properties, respectively. In addition, the average cell sizes had strong relationships with CFA concentration and WF content.