Abstract A perturbation model is used to evaluate the phase stabilities of high entropy alloys. The calculation results can successfully predict the phase stabilities of many high entropy alloys and shows that stable single phase high entropy alloys are rare. The effect of increased entropy cannot balance the fast-increased driving force for the formation of intermetallics. As the temperature increases, the stabilities of solid solutions will increase and the portion of single-phase alloys will expand. The model we propose provides a new paradigm to understand the phase stabilities of high entropy alloys.