An attempt was to synthesis CrMnFeCoNi high entropy alloys (HEA) by mechanical alloying (MA) process, and to fabricate composites Al with CrMnFeCoNi powder by the MA-spark plasma sintering (SPS) process. HEA is typically prepared with equal atomic weight. However, there is no significant difference in the atomic amounts of Cr, Mn, Fe, Co and Ni. Therefore, CrMnFeCoNi HEA were prepared under two conditions of equal atomic weight (at%) and equal mass (mass%). The hardness and constituent phases of those two types were evaluated by micro-Vickers hardness test and X-ray diffraction, respectively. CrMnFeCoNi HEA could be obtained by MA process for 16 h for both at% and mass%. No significant differences in hardness and constitute phases were observed in obtained MAed 16 h powders for both at% and mass%. The MA process was applied to synthesize a composite powder of Al and CrMnFeCoNi HEA. The CrMnFeCoNi in Al decomposed to form compounds with Al during the sintering process. The highest hardness was achieved in the SPS material with 30 mass% CrMnFeCoNi addition, showing 438 HV, more than 250 HV higher hardness than A7075-T6.