Abstract: The continuous aramid fiber(CAF) was added to wood flour/high density polyethylene(WF/HDPE) composites by screw extruder. Surface treatment of CAF with phosphoric acid and silane coupling agent was used to improve the interfacial compatibility between CAF and the WF/HDPE composites. The morphological analysis showed that the surface roughness of CAF increased after the surface treatment. Either the treatment of CAF with phosphoric acid or silane coupling agent, the pull-out strength of CAF bundle increases up to 94.9% and 77.6%, respectively. It shows that the interfacial bonding strength of the treated CAF and the WF/HDPE composites is enhanced. Compared with WF/HDPE composite without CAF, the composite with the untreated CAF results in that the tensile strength, flexural strength and impact strength of CAF-WF/HDPE composite increases by 32.1%, 35.1% and 515.1%, respectively. After CAF treated with silane coupling agent, the mechanical properties of CAF-WF/HDPE composite increase by 42.0%, 37.4% and 550.2%. The dynamic mechanical analysis shows that the interfacial compatibility of the CAF and WF/HDPE composite is improved after surface treatment.