Abstract Multicomponent AlCoCrFeNiMo x ( x values in molar ratio, x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) alloys were prepared using a well-developed copper mould casting. The effects of Mo element on the structure and properties of AlCoCrFeNi alloy were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). It was found that Mo addition took significant effects on the structure and properties of AlCoCrFeNi alloy. Mo 0.1 alloy, similar to Mo 0 alloy, was of single BCC solid solution structure. When Mo content was more than 0.1, the alloy exhibited a typical laminar eutectic structure. The alloy strength was improved obviously, but the ductility of alloy was lowered at the same time. The maximum yield strength reached 2757 MPa when Mo content was 0.5, and the maximum compressive fracture strength reached 3208 MPa when Mo content was 0.3. The strengthening effect and mechanism of Mo addition on AlCoCrFeNi alloy were discussed from different aspects.