An open reading frame (ORF) was annotated as putative trehalose synthase in Deinococcus radiodurans sequenced genome, which has been found in GenBank database through amino homology blast base on combination of bioinformatics. Blasting against the database indicates that amino acid sequence of this ORF has less than 60% homology with the reported terhalose synthases. The function, which was identified by expressing this ORF in Escherichia coli, proves this ORF is a novel trehalose synthase gene. Using the 30% maltose as substrate, about 65% maltose can be converted into trehalose by this enzyme. Recombinant enzyme showed optimal activity at pH 7.0 and 30℃ when it converts maltose into trehalose.