In this article, high density polyethylene/ styrene-ethylene-butylene-styrene block copolymer blends (HDPE/SEBS) grafted by maleic anhydride (HDPE/SEBS-g-MAH), which is an effective compatibilizer for HDPE/ wood flour composites was prepared by means of torque rheometer with different contents of maleic anhydride (MAH). The experimental results indicated that MAH indeed grafted on HDPE/SEBS by FTIR analysis and the torque increased with increasing the content of maleic anhydride and dicumyl peroxide (DCP). Styrene may increase the graft reaction rate of MAH and HDPE/SEBS. When HDPE/SEBS MAH was added to HDPE/wood flour composites, tensile strength and flexural strength of composites can reach 25.9 and 34.8 MPa in comparison of 16.5 and 23.8 MPa (without HDPE/SEBS-g-MAH), increasing by 157 and 146%, respectively. Due to incorporation of thermoplastic elastomer in HDPE/SEBS-g-MAH, 2 the Notched Izod impact strength reached 5.08 kJ m(-2), increasing by 145% in comparison of system without compatibilizer. That HDPE/SEBS-g-MAH improved the compatibility was also conformed by dynamic mechanical measurement. Scanning electron micrographs provided evidence for strong adhesion between wood flour and HDPE matrix with addition of HDPE/SEBS-g-MAH. (c) 2007 Wiley Periodicals, Inc.