Low density AlTiCrNiCu high-entropy alloy (HEAs) powder particles and bulk HEAs were prepared by mechanical alloying and spark plasma sintering. The effects of ball milling time on the alloying process of various elemental powders and the sintering temperature (950 ~ 1050 °C) on the microstructure and mechanical properties of high-entropy alloys were investigated. The results show that the high-entropy alloy powder is a single-phase BCC structure. As the ball milling time increases, the powder particle size first becomes larger and then smaller, and the final powder particle size is about 20 μm. The phase structure of the bulk high-entropy alloy is BCC1 (matrix phase) + BCC2 (Cr-rich phase) + FCC (Cu-rich phase), and the density was between 6.22 ~ 6.30 g/cm_³. As the sintering temperature increases, the metallurgical bonding of the high-entropy alloy powder is more complete and the microstructure is more dense, which is related to increasing the sintering temperature so that there is enough energy between the atoms of the elements for sufficient diffusion. The increase of sintering temperature is beneficial to the metallurgical combination of high-entropy alloy powder and promotes the densification of the bulk high-entropy alloy materials. When the sintering temperature is 1050 °C, the AlTiCrNiCu high-entropy alloy has good comprehensive mechanical properties, and its yield strength, compressive strength, plasticity and microhardness are 1410 MPa, 2000 MPa, 9.13% and 524 HV, respectively. The analysis considers that a high sintering temperature provides sufficient energy for sufficient diffusion between the atoms of the elements. However, TEM analysis indicates that a high sintering temperature also promotes the aggregation of the dispersed FCC-rich Cu phase at the grain boundaries.