Common wheat line N0324, derived from the cross wild emmer (Triticum dicoccoides Thell) accession 5055 and Shaan 253, provides effective protection to powdery mildew. Analysis of 205 individuals in the segregating F2 population generated by crossing N0324 with the susceptible cultivar Shaanyou 225 revealed that resistance in N0324 line was controlled by a single recessive gene designated temporarily as Pm5055. Bulked segregant analysis (BSA) and simple sequence repeats (SSRs) were used to characterize the powdery mildew resistance gene Pm5055. Four SSR markers such as Xwmc441, Xbarc7, Xbarc13 and Xbarc55 were linked to the gene with genetic distances of 10.6, 23, 23 and 23.9 cM, respectively. Chinese Spring nulli-tetrasomic and ditelosomic lines were used to assign the chromosomal locations of the linked markers. The results suggested that this gene might be located on chromosome 2B. Pm5055 can be used to diversify powdery mildew resistance sources in future wheat breeding programs.Key words: Blumeria graminis f. sp. tritici, molecular markers, Triticum dicoccoides, wheat breeding