A DNA microarray was constructed for high-throughput identification of the plant resource of commercial FDSH [Fengdu Shihu (Dendrobium officinale)]. The 5 S rDNA (ribosomal DNA) intergenic spacer region in D. officinale, D. nobile, D. moniliforme, D. hercoglossum, D. williamsonii, D. capillipes, D. wilsonii and D. jenkinsii was amplified by a single primer pair and sequenced. The sequences showed polymorphism. They were incorporated on a glass slide and hybridized with fluorescently labelled 5 S sequences from commercial Shihu. The DNA microarray enabled the differentiation of D. officinale from the other species tested. FDSH could thus be distinguished from its adulterants. It is evident that DNA microarrays provide a high-throughput and reliable approach for the identification of plant resources, and the method presented here is useful for the authentication of FDSH.