Cocktail effect is used to emphasise the enhancement of the properties by at least five major elements. Because HEAs might have one or more phases, the whole properties are from the overall contribution of the constituent phases. Besides, each phase is solid solution and can be viewed as a composite with properties coming not only from the basic properties of constituant by the mixture rule but also from the interactions among all the constituant and from the severe lattice distortion. The Cocktail effect take into account the effect from the atomic-scale multicomponent phases and from the multi phases composite at the micro scale.