Abstract: The multi-walled carbon nanotubes and copper powders (MWCNTs/Cu) composite powders were prepared by high energy milling (HEM), then hot-press sintered to obtain MWCNTs/Cu composite material. The effects of various rotational linear speeds on the grain size and morphology of composite powders and the mechanical property of MWCNTs/Cu composite material were studied. The results show that the grain size of copper powder decreased with rotational speed increasing. At the rotational speed of 4.2/4.8 m·s-1, the average grain size of copper powder reached 23 nm. The tensile strength and microhardness of composite material first increased then decreased with the increase of rotational speed and reached maximum value at speed of 4.2/4.8 m·s-1, which was 187.21 MPa and 166 HV respectively. The shape of copper powder changed from spherical to lamella after milling, and MWCNTs was embedded in copper matrix and undertook the applied loads, therefore improved the mechanical property of composite material.