Phase formation for the multi-component alloys has been predicted by calculating parameter Omega and delta for typical multi-component alloys reported. Here, Omega is defined as a parameter of the entropy of mixing timing the average melting temperature of the elements over the enthalpy of mixing, delta is the mean square deviation of the atomic size of elements. It shows that the high-entropy (HE) stabilized solid-solution is located at Omega >=> 1.1 and delta <= 6.6%. (C) 2011 Elsevier B.V. All rights reserved.