The present invention relates to a composition for epimerization of a non-phosphorylated hexose, comprising sugar epimerases derived from thermophiles, and a method for preparing a non-phosphorylated hexose epimer using the composition. The sugar epimerases derived from thermophiles according to the present invention can effectively catalyze an epimerization reaction of a non-phosphorylated hexose and can easily produce an epimer form of the non-phosphorylated hexose, in particular a rare sugar hexose, and thus can be usefully utilized in the pharmaceutical and food industry.