Thermoplastic vulcanizates (TPVs) based on high density polyethylene (HDPE)/ethylene-propylene diene copolymer (EPDM) blends with different compositions of polyethylene-octene elastomer (POE) were prepared by dynamic vulcanization, the effects of the POE incorporation on deformation reversibility enhancement, mechanical, dynamic mechanical and morphological properties of the TPVs were investigated systematically. Characterization via FE-SEM confirms the tearing strips on the fracture surface of HDPE/EPDM TPVs were formed by the residual plastic deformation of HDPE lamellae crystals, which also resulted in the relatively high permanent deformation of TPVs. The elasticity of TPV matrix was improved greatly by the incorporation of POE and the tension set was decreased obviously. RPA results show that the increasing frequency led to the increased elastic modulus while the incorporation of POE in matrix led to the decreased elastic modulus. The tan delta decreased continuously with the increasing frequency and the incorporation of POE had a non-ignorable influence on the tan delta of HDPE/EPDM TPVs. (c) 2012 Elsevier B.V. All rights reserved.