Magnetic pulse compaction (MPC) technology has the advantages of near net shape, high efficiency and density. In this paper, the effect of aspect ratio on the deformation characteristics of copper powders compacted by MPC technology was studied. Specifically, the compaction velocity, volume strain, micromorphology and micro hardness of compacts at various aspect ratios were obtained. Results showed that the compaction velocity and volume strain increased and then decreased with the increase of aspect ratio. The maximum compaction velocity reached 10.28 m/s at aspect ratio of 1.2. At the same compaction moment, the volume strain was decreased as the aspect ratio increased. Then the relationship between compaction pressure and volume strain was revealed. The aspect ratio range of the optimal compaction effect was 0.6-1.0, and the fluctuation degree of relative density was only 1.03%. The aspect ratio had less effect on the micromorphology distribution in the axial direction of the compacts. The micro hardness value of the upper surface was higher than that of the lower surface, and the edge position was greater than the center position. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.